After a web search I found these:
https://support.microsoft.com/en-au/...f-2a14c417f84c


Go to the Desktop, right click on blank space, hover on 'sort by' option and choose 'alphabetical order', either 'ascending' or 'descending' according to your wish. You will notice the change.

This answer directly above was borrowed from https://brainly.in/question/53458741. Thanks to the smart one whom answered that question.

Why the system changes this I don't know, perhaps because you attempted to arrange the icons manually instead of via system command and thus after a computer reboot/startup it reverts to the previous setting of how the icons were arranged.