There are two types of Boosts: Pre-Game Boosts and In-Game Boosts
Pre-Game Boosts give you a head start in the game; start with fewer colors, or with 3 extra moves.
Buy Pre-Game Boosts by tapping on the price tag shown below the boost you wish to buy.
If you wish to use Pre-Game Boosts just select them at the ‘Play’ screen.
In-Game Boosts
help you tackle that difficult level whilst in the game; change the color of the surrounding Jellys to make that crucial combination on a Color Combination Level, or remove a column and a row to bring down that very last Diamond.
Buy In-Game Boost by tapping on them; select them for use by tapping on them at any point in the game.
In-Game Boosts can be bought in one game and saved to be used in another.