left my 4wd on

hi my rancher 420 fe i was gone over rouf terain river crossing had my 4wd on to cross but i then forgot to turn my 4wd off 🙁 never noticed it tbh…someone said to me that its bad job to have 4wd on driving fast…i was driving for bout just under 1 hour ..anyone tell me iff this is bad or ok thanks very mutch
also do you have to stop before changing from 2wd to 4wd? thanks