Correcting taking putter outside the line?

[EdZ]

I have been at best, a mediocre putter all my life.
I am right eye dominant which I must adjust for but the major problem is that I take the putter back outside the line on my backstroke. What is the best way to work on correcting that problem?
Thanks

Very often that happens with either or both of these are true:

your hands are too far 'inside' your shoulders (verticle plane)

your eyes are too far 'outside' your ball/target line

(basically both can happen if you are leaning too far out over the ball)