I switched from tulip domes, which I loved, to custom molds when I switched to the power receiver. They were OK but I missed how well the tulip domes fit and felt.
I thought with the custom molds that the receiver wires were too long but not long enough to change. There was just a little slack in the wire.
Well… I cleaned the molds a few times and I was always careful to note their positioning before I took them off the receiver. Then, this last time, I forgot to note the positioning. So after cleaning I looked at them from every angle and decided since there were only two ways to do it, I would just have to try each way and see which orientation was right.
When I got them right they went further into my ear than previously, and they don’t move. Before, besides having a little slack, they would work their way out a little.
So they had been upside down from the beginning. Now that I have them oriented correctly, I see what everyone else has been saying. I do like the molds better than the domes, although the tulip domes were very comfortable and I had no occlusion. When I had the impressions done the audiologist did deep impressions and I really don’t have any occlusion because of that.
So, oriented correctly, the molds really do fit better. 
I have the small, soft Westone mold (from Costco), and the orientation is that the receiver wire comes out of the mold at the lowest position possible, not the highest. You would have to see one to know what I mean, but originally mine were oriented so the wire was on top, and the vent was on bottom. Now that the wire is on bottom, it takes up the slack and the wires are perfectly up against my head and going around my ear right at the base of the external ear.