You shouldn't have to change anything on your VCR. Mine plays well with my digital cable.
If you want to tape programs on channels that are only offered through digital cable or are scrambled, you need to make sure that the signal goes from the wall, to your cable converter, to your VCR, then out to the TV. And your converter has to be switched on. But you knew that
What specifically is going wrong? Is it recording the wrong channel, recording static, not recording anything, what?