I have been using wide band condom catheters for my father for about a year now and they had been working great staying on, but I recently received a bad batch the catheter just falls off or doesn't stay on for too long and constantly leaks. My father is bedridden, and I am trying to see how to keep the catheter on.
Otherwise, you can try to makeshift something with medical tape to tighten it or attach some of the adhesive to part of the shaft and on part of the catheter (assuming the condom part doesn't reach too far). Maybe its an issue of the adhesive not sticking properly (if the ones you have use adhesive) and cleaning could help. If it's an adhesive+size issue then making a loop of double sided medical tape, placing that first on the shaft, and then putting on the catheter?
Maybe an extra large condom with a hole cut in it and slide that over the whole shebang?
Lmk if you have more info about why it's falling off and I might have some more precise ideas! Best of luck.