Configure Linux Mint 21
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Add taskbar
The left monitor must be the "primary". If necessary, switch monitor positions by dragging and click "Apply".
Add applets
Right monitor: navigate to "Grouped window list" and click on the + sign. Some icons become visible at the bottom right. Probably a bug, but is hard to see those icons. Close the "Applets" window.
Right monitor: Drag those icons all the way up to the left side of the screen (still on the right monitor!) until the mouse cursor changes in a "hand with arrow" and release the mouse.
Configure update mirror
Click in the field "Main (...)". Another window appears. Select the repository with the fastest speed. In this case, let's choose "LiteServer" and click "Apply".
Install updates
Confirm the (possible) message concerning additional changes. Again, the password of "guru" is asked.