Moving over the screen the cursor sometimes changes from theme
Every desktop has its own way to select the cursor theme
Because we want to have a consistent cursor theme we have defined on all our desktops that we use breeze snow.
Navigate to this folder /usr/share/icons/default
You will find the file index.theme with this content (fix for mouse in plasma changing all the time).
Change here also to the correct cursor theme
If you want an other cursor EVERYWHERE, you need to change this one too.
THE CURSOR theme IS NOT APPLIED?
DID YOU TRY
TURNING IT OFF
AND ON AGAIN