We can customize the Xiaomi smartphone's Quick Ball or Access Tool as we like. We have five assignable fields, each of which has a different function. If we
want to add a function or shortcut, it replaces another, previously selected one. The following shortcuts can be selected:

Note: In this manual we will only change one shortcut, others can be set up or defined in the same way.

Android 10 (MIUI 12.0)
Step 1:  Open the  Settings
Step 2:  Tap on  Additional settings
Step 3:  Tap on  Quick ball
Step 4:  Tap on  Select shortcuts
Step 5:  Choose a  shortcut  to replace
Step 6:  Choose a new  shortcut
  1. Open the Settings
  2. Tap on Additional settings
  3. Tap on Quick ball
  4. Tap on Select shortcuts
  5. Choose a shortcut to replace
  6. Choose a new shortcut

Xiaomi Instructions