I wanted to know if i have data already stored in a user share, then if i change the disks that the share can use either by changing the included or excluded disks, will that move the data from a disk that is no longer included or will it stay where it was until it is moved?

unRAID never moves files except for the special case of moving cache-yes user shares from cache to array and moving cache-prefer user shares from array to cache. It never moves files between array disks no matter what changes you make in share settings or disk assignments.

Also, User Share settings only affect how new files for the share get written. Reading from a User Share includes all disks except those excluded from all User Shares in Global Share Settings.