Cant edit drum notes in bar without it affecting original other notes on other stave lines

The problem that I am experiencing is that, for example in bar 93 of the attached file I want to add extra bass drum and snare beats to it but each time I try this it pulls down the beats from above and changes the rhythm, I’ve obviously changed something in the edit drumset by accident, I have looked through the forums to try and find a solution to my problem but it’s not mentioned anywhere, so help would be greatly appreciated, thanks.

Tom Cleugh