Welcome to Just Answer
Do you mean the tank keeps filling on its own
not sure. periodically i hear the sound of the toilet flushing when no one is in there.
The flush valve seal is leaking, and when it gets low enough it refills like it does after when youflush it
where is the flush valve and can i change it or replace it myself?
look in the tank , see if it has a chain hooked to a flapper and the other end to the toilet handle
yes it does. do i replace a component or the full assembly?
Just the rubber flapper, take it with you, so you get the same one
what is the brand of your toilet
Tell them at store, because you need to get a kohler replacement as they are sometimes different sizes
ok. thanks. happy new year.