Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Uninstall the most recent Windows update to see if it makes a difference on your system.
That won't be necessary.
Go to System settings
Select Display
Under Scale and layout, go to Advanced scaling settings
In the panel, enter a large number (i.e., 200)
Click the Sign out now link
Sign out and sign back in.
Your display should be particularly large
Go back to System settings
Select Display
Turn off the custom scalingand select 100% if prompted.
If necessary, sign out and sign in again.
Your ribbon should look normal now. The settings were stuck and you just "unstuck" them.