You may have to just keep trying things because it could be the receiver wire is too long, or too short, or the soft tip is too large or too small. I had better luck with the tulip style tip/dome.
You can check yourself to see if the wire is too long or too short. When you push the receiver tip fully into your ear (if the wire wasn’t there you would probably not be able to see it at all, when pushed in fully), the bend in the wire should be about where the opening of your ear is, and the wire should look like it comes straight out and then goes straight up against your head.
If the bend in the wire is being pulled almost straight when you push the tip in, the wire is too short. If there is still some play in the wire when you push the tip in, the wire is too long.
An alternative is to have a custom mold and that MAY solve the problem. You can have a deep mold made with a large vent to almost completely reduce occlusion, depending on if your level of hearing loss allows a large vent. I know everyone here says that a custom mold will solve any fit problem, but mine still manage to work out a little when I eat, or after a few hours of just sitting in my ear. The tulip domes fit the best for me, and no occlusion.