Thanks for your replies.
I use the NTFS file system (it's a 1TB disk which is filled for 95% so I could not change that before I added it to my lmce setup).
I tried the chmod 777 .* and chmod 777 * after entering su modus in terminal.
The chmod 777 *. seems to work (no error) but with the 777 * command I get the error message
cannot operate on dangling symlink '10WADS External (sdf1) on dcer 
When I open File explorer in KDE and check the user rights for the folders nothing seems to have changed.
Is there maybe a command to open the file explorer as root? Than I would be able to just move the folders back to root as I did in the first place when moving them to the user_1 folder.