Setting controls

My old PC died, so just built a new one. Reloaded the game and the first time I played, everything was as expected. But, the next time I logged in, some controls have changed and I can’t get them back. I am specifically talking about the gun view (sniper mode) in ground (tanks). It used to be when I clicked my right mouse button, it would zoom my gun view in, then I’d click it again to zoom out. Somehow that control was deleted. I re-added right mouse button for camera zoom (I assume that’s the correct control), but now, I have have to hold the button down to have the zoomed view, it doesn’t toggle like it used to. How can I fix this?