Sounds like you are applying back pressure too early in the steep turn. It certainly could be from the change in seats, but regardless, you shouldn't need much backpressure until you pass 30 degrees of bank. Practice rolling to a 30 degree bank left and then back without gaining altitude.
For the lazy eight, remember that you should be constantly decreasing the bank in the second half of the turn. The suggested (key word) bank is 15 degrees at the 135 degree mark. You may be coming out too quickly from the bank, so keep an eye on that.