How can I change the files in Ubuntu /snap folder?

Question

I install IntelliJ IDEA from Ubuntu Software Center, I wanna change ${IDEA Folder}/bin/idea64.vmoptions .

The full path is /snap/intellij-idea-ultimate/91/bin/idea64.vmoptions

When I try to change this file, it returns "Read-only file system"

Answer 1

During registration with a serveer I was getting ticket obtaining prohibited

Under linux/snap to register with the server:

I had to open the app and go for a free trail, then as @CrazyCoder said go for Help, Edit custom vm options and add -Duser.name=myUserName then restart and go for Help, Register and then set the license server...