The gold in your pile is only for savings. You cannot hire more crewmembers, or buy from the Island Shop with that gold, until you “claim” it. You can also only save up to a certain amount of gold in the pile. That maximum number is written below the bar, next to the CLAIM button. To keep storing gold, “claim” your pile and start over again.
If you have more questions, please contact us through the game by going to our Menu > Settings > Support. We can help you quicker this way, because the game will allow us to view your account and better help you.