Default [Q] Connecting phone to the computer

Hello

I got simple problem with my s4 HOS phone. When I plug it to my computer, USB debug mode become always available, nevertheless I did turn off debuger tools. Becouse of that i got certain problems with tranfering files between devices. Is there any solution?
Other thing I did noticed is since I plug this phone with computer my USB memory became unavailable, before that as far as I remember It was good and have something about 2gb of memory free..

In addition my pictures transfered to computer are much more worst than pics seen on phone screen, They are discoloured and very bad quality

Phone is clear, never touch any new rom or nothing else. Clean JB 4.1.1 rom. S4 ver
Have you got any idea whats wrong or what can help me?

Thanks