To switch among different organizations you have joined in, please click your profile picture and click on the org you want to switch to as pointed by the red arrow below.

Usually, you don't need to restart the Teams app.

If the issue persists, try the Teams web app ( https://teams.microsoft.com/ ) instead via an inprivate browser window to check if any difference.

(The inPrivate browser window (for Microsoft - Edge browser)

 Incognito browser window (for Google - Chrome browser) is a browser window which will not save the browsing data (like your history, temporary internet files, and cookies