Poor me I had to do all the OW cert training like that (I didn't know back then that actually everything can/should be done neutral buoyant). Kneeling position is very uncomfortable for me even on dry land, without equipment etc - let alone underwater. What my instructor told me to do and I found to be much more comfortable was to keep one leg in front of me i.e. the position shown in this picture https://goo.gl/images/cVhAaf
It worked for me and I am sure it will help keeping your balance too. Still not perfect as I had to change leg every now and then but much more comfortable and stable than just kneeling.
It worked for me and I am sure it will help keeping your balance too. Still not perfect as I had to change leg every now and then but much more comfortable and stable than just kneeling.