Just purchased the Klipsch Custom 3 which I enjoy, however my left ear piece keeps slipping out. I am using the largest earpeice but still slips out after a few moments and movement. Any suggestion?

I am looking for feed back on the Klipsch-3. I am sick of the cheap store bought IE's, to include the BOSE. I am new to the high end IEM but have grown fond of what I am reading about the Klipsch-3. Does anyone have feedback on this type of IEM? Most inportant to me is sound (of course) but...