When i open another persons save it comes up and then i open it, but it does not allow me to edit on to this e.g. the acid when drawn stays in one solid lump in the air, even after gravtiy is switched on and i have signed in. It's starting to get pretty annoying so help please? :)
Is it paused? (Press the spacebar)
If it isn't paused, have you checked both types of gravity? In simulation options (click tick button in bottom right corner), there's a checkbox to turn Newtonian gravity on or off, and a dropdown for Vertical/Off/Radial gravity.