I have replaced my above counter sink with an under mount sink and new quartz counters. Now the disposal does not line up with the plumbing drain. It needs to be 4 1/2 inches from the sink instead of 6. Is there a solution to this problem?

4½ inches how? Forward or backward, left or right? A picture would help.

I think the OP is referring to the height of the drain. There may not be an easy solution. Pictures will greatly help.

I thought of that, but couldn't make sense of it. All the disposals I have used attached to the bottom of the sink, not further beneath it. Is it the drain that needs to be 4½ inches below the sink? Is the disposal now too low?

This is pretty typical with countertop replacement.

If the 4-1/2" is a lateral offset, that you swing the trap u bend all the way towards the outlet and still miss by 4-1/2", you can always put in a 45 elbow to the wall outlet.

If it's the wall stubout being too high, which is also very typical because old sinks are 6" or 8" deep, new sinks are 10"+ deep so even if you top mount you are 2"+ lower than the previous sink. Now you want undermount that further lowers the sink by the thickness of the countertop plus plywood backing, this can easily add up to be 4"+ lower. I replaced a countertop last year and went from a 8" top mount to a 10" sink, I did the calculations and the height won't work so end up top mounting it instead. The solution there is first look for a low profile disposer and read the specs carefully, or lose the disposer altogether. Opening the wall and lowering the entire trap arm and santee may be too much work for the average homeowner especially if the santee is over a few stud bays behind drawers or corner cabinets.