A Unity ID allows you to buy and/or subscribe to Unity products and services, shop in the Asset Store and participate
in the Unity community.
This one is very useful and easy :
To save to another mesh, go to :
Top Menu > Tools > Polybrush > Bake vertex Streams > Batch option : create a new composite mesh
Then update your...
Sometimes it could be solved by unchecking VR compatibility in player setting (Edit > Project Settings > Player / Virtual reality...