There are a few things that might help, e.g. hiking out and angling the board to windwards with you, keeping the board down with more front foot pressure or taking the wing more above your head like Mary Poppins and releasing pressure with your backhand (easy for a windsurfer as you obviously are one),
but mainly it's time on water, Somehow many things magically align after a few sessions and you start wondering what the problem once was.
Go out and have fun!

Unless you have some very specific foil that has an enormous amount of lift at very slow speeds that would then change as the speed increases you should not have to change your feet placement after take off. The very same place where you stand while not yet foiling should work for getting going and then for foiling as well, and for doing all the maneuvers like jibes (if not switching feet) and for tacks and for 360s etc. If your setup requires stepping around it's not a beginner friendly foil, and if that's the case I would suggest somebody experienced to look at your setup and perhaps tweak it a bit.