Facing issues with screeen display...... sometimes screen went off (blank screen) and have to be switched on again............ This is quite irritating.....
Also MSTeam software is not showing "Chat" option while logged in.
You can change your screen timeout by going to Settings -> Display -> Screen timeout. On the Samsung tablets there are two settings which affect how long the screen stays on, the screen timeout and Smart Stay, which keeps the screen on if it detects that you're looking at it.
If you are usng an app and the display is not staying on then you should contact the developer and report the bug.
As for Microsoft Teams, I did a quick Google and there are lots of Android Issues. You should log in to the Microsoft Teams forum and ask for help there.