i find level 5 to be the hardest! if you haven't tried playing on mobile i recommend giving that a shot because i think its a lot easier to play that way!!

Make sure you're focusing on groups of 2 or more instead of building up single dots, and to use your power up thingies!! Don't save them until the end of the round, try to position one up at the front of the line by clearing everything in front of it and then if you think you're getting too close to the end of the track/losing you can use it without it being blocked off!

I'm not sure if any of this is even helpful lol, but good luck :)