Restoring sorting; F5 any function?

[Subjektiv]

Please Help!
After moving and mixing some thumbnails for a special sorting I want to restore my desired standard sorting, like name, filetype etc.
Yes, with the mouse I can klick on "Sort by" ... but I want it by shortcut.
I guess, pressing the function key F5 should be the quickest method. Am I right?
But F5 does nothing...

Any advice?
Thank You

[xnview]

there is no shortcut, F5 refresh thumbnails