Hi Hurdity and everyone :
Prolapses become a problem when they become uncomfortable eg a constant feeling of a dropping/dragging feeling and/or the sensation of a tampon slipping out. In the bad cases, they protrude and are tangible. Sometimes they can be accompanied by a low backache, especially if you have a rectocele.
They may become a problem in sex and present as an obstacle to your partner. Can be very offputting to him.
Sometimes you feel as if you are sitting on an egg at the front - or like sitting on a sausage at the back - and whichever kind of prolapse you may have, the organ concerned gets harder to control with associated symptoms of leaking when you sneeze if you have a cystocele - and it being hard to keep clean if it is a rectocele.
This is my personal acccount of the main symptoms of mine when the prolapses became a problem. Pelvic floor exercises do help, as does avoiding too much heavy lifting.
Hope this helps.