Hi,
Ideally, you should cut at the highest level all around the 3 areas... It may not take much off initially, but it will get the grass at the same height.
When you say "bump", do you mean that the ground in bumpy? or is the grass growing in "clumps"? If you had a pic, might make things easier to see...
So, I would recommend, cut at the highest setting for the moment, gradually dropping the cutting level over a period of weeks. You shouldn't drop it to the lowest level as your grass may not be healthy enough for such short cuts.