It`s a bit difficult to visualize what`s going on there, but it sounds like you have a wide, thick belt that is pretty much riding where it wants to ride. Perhaps you could work the leather by rolling it along the length of the belt repeatedly, in both directions. I have no idea why the belt would need re-tightening once put on, but I think all kilt belts need to be adjusted as far as the position on the body through the course of a day. I think the belt needs to ride entirely on the waist, if it is partly on the hips, I could see where that could cause problems. Maybe a 3 " belt is just a bit too wide for you? Just some thoughts, hope it makes some sense.