Classic Questions about party sync

Can anyone help me understand party sync? I’m trying to play with friends who’re levels 20 to 50+. When we join a dungeon through dungeon finder it’s all good – everyone’s challenged. When we’re doing world quests or walking into dungeons (we tried Rage Fire Chasm), the high-level characters are able to one-shot everything.My expectation was that all mobs would change to an appropriate challenge regardless of where we are/what we're doing. Are we doing it wrong?((weirdly, we were questing just north of Org and everything seemed to be scaled appropriately; however, my party-members vanished and I realised I was still on Pandaria time-walking (don't know why I could see them in the first place, but I digress); when I dropped the time-walking, the mobs were no longer scaled.)) via /r/wow https://ift.tt/3bK496g