His problem is, I'd assume, not that he doesn't know how to do it, but that it doesn't actually work properly.
Tried it myself too, removed both e-pawns, put one on e4 and tried to change the colour. It didn't do it first time. Did manage to change it eventually, but not as it should be. And lost the h1 rook in the process.
A second attempt saw the g1 knight change colour without me actually clicking on it. Actually managed to post that one up on the open invites. In the time it took me to write a short PM to the person accepting as to why I was about to delete, they removed it.