When you press down, it is done by intervals, first time by 9 and the second time you press down by 7 and same goes when you go up (by 5 first and by 3 the second time you press up)
The goal is to reach level 51 (same as the level) and you start at level 50. This is a tricky level but here is a fast trick.
First, go down once (so you will reach level 41) then go up once (so you will reach level 46). Now tap/press fast up again 3 times. If you do it right, it will go up by 5 instead of 3, reaching level 51 (46+5). If it stopped at level 49, just quit the level and reload it again.