Problem:
You are wearing the wrong band size, straps are not adjusted correctly, bra is old and it is time for a new bra, or you are wearing the wrong style.
Solution:
If you are wearing the wrong band size, go down in the band and go up in the cup. If you are now wearing a 34C, try a 32D.
Make sure your straps are adjusted properly…..not to tight and not to loose.
Look for a bra style that the straps are closer to the back hooks which are sometimes know as U-back, or modified racer back.
It may be time for a new bra. 🙂