i can add behavior Packs and replace world and more

i want to add behavior pack but not exportet and i was try to replace world with behavior Packs but that same just resource pack can i added before i add behavior, also this bugs to ANNOYING i cant after i try longs time like this really bug i cant add more option at edit world,cheat,ticks and reset world i can download world but yeah some behavior stuck after i check, this is real bugs ever at Minecraft Realm long years