How do I fix this?

If player have more then 1 coin he can buy a new screen. And he must do it only once. But every time he touches sprite 11 he lose 1 coin. How can I fix this?

I would create a third condition for buying the new screen, which could either be a global or instance variable.

For example, in order for a player to buy a new screen, I'm assuming the action has 2 conditions, 1) he touches the sprite, 2) he has more more than one coin. What I would suggest doing is creating another action when the screen is bought that sets a variable (for example we'll call it 'bought' to 1) and you give the event a third condition that 'bought' must not be equal to 1.

Sorry if this doesn't make too much sense, I hope it helps out a bit!