I tried to study English as Starbucks, but it was too noisy. So I changed my mind and decided to study at home.The difficulty of using "I changed my mind" is related to the listener's knowledge. It's fine to say:
I went to MacDonald's and ordered a cheeseburger. But then I changed my mind and ordered a Big Mac.This is OK because the listener knows the menu items at MacDonald's. The listener knows what your options are at MacDonald's.
The original mistake in class tonight can be fixed by telling the listener the options at the start:
I wasn't sure if I should study at Starbucks or at home. I tried to study English as Starbucks, but it was too noisy. So I changed my mind and decided to study at home.That's fine.
Please use English well!