press escape/click on the flashing button on the left sidebar
Yes this made it easy... I only noticed the speed one before, that's a really dumb mistake on my part, thank you!
Also, just like the user haidi5200 (highest comment at the time I'm posting this) I don't know what to do with the foxes on the left and right in world 3, I'd really appreciate a hint for those...
I've noticed that I lose health if the foxes and harpies are together too long, but if the purpose is just to keep them away from one another I don't understand the win condition (or maybe it just goes on for a while?)