I've been trying to find a solution to this for ages - with all other attempts failing - and finally came up with a solution what works!
Caveat: This is using Buster on a RasPi4, and I've not tested on the other OSs or Pis.
Locate your desktop-items-*.conf file. Mine are in ~/.config/pcmanfm/LXDE-pi.
Use sed to replace the filename in the ...