In Planning, click on pencil icon next to specific user. You can access the settings also via User section by clicking on Edit button
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Please note that only users with roles such as Team Leader, Managing Director, CFO, or Admin have permission to modify Daily capacity settings.

you can hide the user from planning as well from here via the checkbox "Show user in Planning"

To adjust your profile color, click on "My Profile" in the upper right corner of the screen.

Choose a color according to your preferences.

All allocations created by you will adopt the selected color.

Admins or team leaders can change other users' color in settings in the User section which you can access by the process mentioned above