You clicked Share in a meeting, and either the wrong screen went out, or the window you wanted was a black rectangle to everybody else.
Two things you have never looked at decide both of those. One is how many displays Windows thinks you have, and the other is a permission list Windows keeps for screen capture.
I read both of those on this machine before writing, and the second one had entries on it that I did not put there.
Count your screens before you click Share
Ten seconds, and it is the reason the wrong thing goes out.
⭐ Share offers you one entry per display, and they are labelled by number rather than by what is on them.
⚡ This machine has three displays, at 2560 by 1440 and two at 1920 by 1080. Picking blind is a coin toss between three.
⚠️ Move what you want to share onto your main display first. Which one Windows calls 1 is worth settling once.
⛔ Or share a single window instead of a screen, and the number stops mattering at all.
Window or screen, and why it changes what leaks
The choice most people make without reading it.
⚡ Microsoft's own route on its share your screen page: "Choose the screen you'd like to share or select Window to select from open programs".
⭐ A window shares only that program. Notifications and everything else stay private.
⚠️ A screen shares whatever lands on it, including a message banner arriving mid sentence.
⛔ Share a window when you can. It is one click different and much safer.
Why is the shared window a black rectangle?
Three causes, and only one is your fault.
⭐ A window that appears black to everybody else is usually protected content. Streaming apps and some banking pages block capture deliberately.
⚡ A minimized window shares as black too. Windows has nothing to capture from it.
⚠️ And a window on a different graphics processor can come out black on laptops with two of them.
⛔ Sharing the whole screen instead sidesteps all three. Accept the trade for that one moment.
The permission list nobody knows about
This one is ours, and it is what I went looking for.
⚡ Windows keeps a per-app record of screen capture permission, separate from anything the meeting app asks you.
⭐ On this laptop the general capture permission is allowed, with two apps recorded, and a second borderless capture permission is allowed with four.
⚠️ I did not grant those knowingly. They are recorded the first time an app captures the screen.
⛔ It sits with the microphone and camera lists. Same part of Settings, and just as unread.
What the other people see and hear
Two lines from Microsoft, and one of them surprises presenters.
⭐ Microsoft states the consent step: "Other chat participants will receive a notification to accept your screen share. Once they do, they'll be able to see your screen and continue the chat."
⚡ And the sound: "Screen sharing opens a muted call." You are not being heard until you unmute.
⚠️ That is the classic two minutes of silent presenting. Unmute before you start talking, not after somebody types it in the chat.
⛔ Microsoft also names a platform limit: "Linux users can't share screens in a Teams chat at this time."
No sound in what you shared
Four causes, and the first is the commonest by a distance.
⚡ Sharing a window rarely carries system audio. Sharing a screen with the include sound option does.
⭐ The include sound tick is off by default in most meeting apps, and it is next to the share button.
⚠️ The browser version of a meeting app has tighter limits than the installed one. Which is also true of the microphone.
⛔ And your output device matters: if sound is going to headphones, that is what gets shared.
Before the meeting rather than during it
Five, and doing them once is the whole difference.
⭐ Move the thing you are showing onto your main display.
⚡ Close or move anything you would not want seen, because a screen share includes the taskbar.
⚠️ Turn on do not disturb so no banner arrives while you are presenting.
⛔ Then test with one person before the room fills. And check the microphone in the same minute.
Status: display layout and screen capture permissions read on this laptop, 29 August 2026, Windows 11 Home 25H2, against Microsoft's own screen sharing guidance. ⛔ No meeting was joined, no screen was shared or recorded, not one app is named on this page, and nothing was switched on or off.
Why is my shared window black to everyone else?
Usually because the app blocks screen capture on purpose, which streaming services and some banking pages do. A minimized window shares as black too, and on a two-graphics-chip laptop a window on the other chip can. Sharing the whole screen gets around all three.
How do I share sound when I share my screen?
Use the include sound option next to the share button, and share a screen rather than a single window. Sharing a window rarely carries system audio at all. Whatever your output device is playing is what gets shared, so check that first.
Does Windows keep a record of what has captured my screen?
Yes. There is a per-app screen capture permission list alongside the microphone and camera ones. On this laptop the general capture permission is allowed with two apps recorded, and the borderless capture permission is allowed with four. Entries are added when an app first captures.
Why can nobody hear me while I am sharing?
Microsoft says screen sharing opens a muted call. You are sharing and silent until you unmute. It is the commonest two minutes lost in any meeting and it is not a fault.
The Short Version
- Count your displays first. Share lists them by number, not by content.
- This machine has three, at 2560 by 1440 and two at 1920 by 1080.
- Sharing a window keeps notifications and everything else private.
- A black rectangle is usually protected content, a minimized window, or the other graphics chip.
- Windows keeps its own per-app screen capture permission list.
- Two apps are recorded here for general capture and four for borderless.
- Microsoft says screen sharing opens a muted call, so unmute before you speak.
- Sharing a window rarely carries system audio. Share a screen with sound included.
Where to Next
Work out how many displays you have before your next meeting, not during it.
Move whatever you are showing onto the main one, then share a window rather than a screen.
Turn on do not disturb first, because a screen share includes every banner.
Unmute yourself the moment sharing starts, since Microsoft says the call opens muted.
And if an app of yours shares as a black rectangle no matter what, tell me which one in the comments. That list is worth having.
Isaac Smith is the founder and editor of PC Glance, a website that covers computers, laptops, and technology. He is a tech enthusiast and a computer geek who loves to share his insights and help his readers make smart choices when buying tech gadgets or laptops. He is always curious and updated about the latest tech trends.