1. You can make the filaments easy to remove if you ALWAYS first let it melt and extrude a few mm before having printer unload the filament. Melting and extruding a bit gives you a fresh, soft filament end that cleanly comes out. You can do so via the setup menu. Heat up your extruder and then advancing the e-axis. This prevents formation of thick filament ends.
2. You can also add a collet clip to help lock down the PTFE tube. Prusa doesn't include one, but you can print one out of PETG. Adding the collet clip requires removing the entire extruder. Once removed, push down the PTFE until it full seats. Pull up the collar while continuing to push down the PTFE tube. Slip your locking ring under the collar to hold the collar in its up "engaged" position. https://www.thingiverse.com/thing:2585970
(Unrelated to Your Main Issue)
BTW, please check the axle pin of your extruder idler. It looks like one pin end is flush with the outer edge of the mount. The supplied pin is a bit short and typically must be positioned with both ends recessed to solidly engage BOTH sides of the mount.