Additional meeting and call-related features and issues within Microsoft Teams for business
Yeah strange that I have the same Dell with Office 365 now when Teams first came out you could change the back ground on the Dell as well as my Desktop then there was an update and it disappeared off the laptop and played up on the Desktop ok the desktop the button was there you click on it and it opened the menu but there were no backgrounds or choice to add your own. Fast forward another update on Teams it worked intermittent (still not on laptop) I found that before joining a meeting if I opened the Teams app instead of the email link that is sent by whoever is running the meeting I have all the background options leaving it open I joined the meeting and freely able to change background. But tried on the laptop the option button isn`t there.
Further back on this thread someone from Microsoft said it doesn`t work on laptops - Oh the fun of Microsoft