Changing accounts

My 3 each kids have their own Ipads. They have been set up With the same apple account so when one has get a New app it shows up on the other ipads too.

We are now looking to get the the Family edition of Apple Music and setting up the 3 iPads With seperate accounts. Can I just change user ID's on their ipads? Will all the apps they already have downloaded be erased? Not all that interested in bying apps 3 more times.......