I am doing a project and when I try to clean up my topology the snapping goes all over the place. I have opened a new file and put some loop cuts on a square and it works no problem, but in this 1 project try to snap 2 vertices together and it will jump to anything but the one I want. Any ideas what to look at?

Thanks.

I am doing a project and when I try to clean up my topology the snapping goes all over the place. I have opened a new file and put some loop cuts on a square and it works no problem, but in this 1 project try to snap 2 vertices together and it will jump to anything but the one I want. Any ideas what to look at?

Thanks.

I think I didn't explain well enough as pictures show below if I double g and slide the 3 pixels to the other 3 when I click the mouse everything jumps over to the right. How do I stop it? and what's going wrong?