There's no mouse out event right now. Do it like this:
Mouse is Over JUGAR - > Jugar2 Set Visible (Assuming Jugar2 is on top)
Trigger Once
Mouse is Over Jugar (inverted) -> Jugar2 Set Invisible
Trigger Once
Or
Mouse is Over JUGAR - > Jugar2 Set Visible
Trigger Once Jugar Set Invisible
Mouse is Over Jugar (inverted) -> Jugar2 Set Invisible
Trigger Once Jugar Set Visible
Also you don't have to create 2 sprites for a button just create one sprite and set frame1 to normal button state and frame2 to over button state and change frame on events accordingly. And remember Trigger Once is your friend. You'll be using it alot