does 18-55 make little sounds when you open the camera? disable pre-af. I guess 18-55 tries to back default mode when you click to preview and that sounds belongs to it.
I would not change them, but would sell my kidney to get the other three.
btw ı have samyang 12, 35 1.4, 56 1.2. I also tried 23 1.4 and 90 2. out of those I believe the 23 1.4 is the best.