OK, some guy written comment is not possible to beat 19, 21 levels with 3 stars. Here I did that, pretty easy this time. Sometimes it took 10+ tries to get 3 stars on some hardest levels.

Hint for level 19, after 2nd shot you should have 14+ balls. Almost no way to get 3 stars with less.

Hint for level 21. Break the spot where there is a range balls and breaker balls together. Also don't shoot to the range ball directly but a little aside, so you can grab more balls this way with range balls.