There is an annoying clicking sound happening even if I have the metronome off.

Do you have “Pocket operator sync” enabled in settings? (see below.) If so, PLEASE disable – pocket operator sync is for if you want to sync your Pocket Operator with koala – if you don’t have a Pocket Operator, or don’t know what a pocket operator is, PLEASE KEEP THIS SETTING SWITCHED OFF!!!! If you do have a pocket operator and you want to sync it to koala have a look here: