I only do this against the computers. Because it can be time consuming and it doesn't guarantee yahtzee's. it just lets you see all your options before choosing to hold any dice.

Use all 3 rolls and write all 3 combinations down. Close the app. Delete the app, then re download. When you log back in you can re roll, but you will roll all the same numbers. Now when you select a dice, it replaces the number next in line. Except for your first roll, unless you've chosen to keep the first dice to carry on into your second roll. So if I roll: 14644, 32441, and a 11166. I'd carry all three 4's into my next roll, turning it into 34244, when I roll the third time it'd be 44444 making A Yahtzee. It takes a while to get used to using the numbers you are going to roll benefit you, but once you get the hang of it, it makes more and more sense. It's really helped me a lot with playing against the computer