the redlines are not working properly anymore. They are jumping around the screen. how do i get it back to how it was?

I use the redline function of Adobe often and I used to be able to zoom in and put them EXACTLY where I wanted them, but now they JUMP all over the place and won't be exact enough for me.  How do I get them back to the old way where you could make them VERY specifically go exactly where you want them?