Should you seal both sides of the ailerons and elevators or can you just seal one side like the bottom? Also, how about the rudder....any need to seal these?

Thanks in advance.

I seal both sides on my airplanes but it all depends on where the exhaust goes while your in flight.

Seal them all. You only need to seal one side unless the surface will have problems with fuel getting on both sides and debonding the covering.

my english is bad, so can someone tell me what is sealing?

Sealing is to cover with clear adesive tape or covering material
the gaps between the plane and the control serfaces IE: rudder, elevator, ailerons...

why do i need to seal at all? my hinges are glued. when I was cowering my plane, I cowered ailerons and wings separatelly from all sides and then glued hinges.