Flats and Sharps in Greensleeves
I have a quick question regarding flats and sharps. Due to the coronavirus, I am stuck at home and re-learning the piano :)
Yesterday I was printing out sheet music and I printed out Greensleeves. I know how to read flats and sharps but there are some notes where they don't have the sharp or flat at the beginning of the sheet music but you still somehow have to know that you have to add a sharp or flat to that note.
For example in Greensleeves, it never specifies that there has to be an F#. How do I know when to play a note that needs to have a sharp or flat when it is not specified?
I hope I was able to ask this clearly :)