I am not sure if this only happens to me.
According to this page:
https://docs.moodle.org/37/en/Working_with_files
To update a file, go to its original location (for example Private files) and upload your new version with the same name. You will be prompted to override or rename the file. Choose "override" and this file will replace your original file and the alisas/shortcuts will remain and all be updated to your latest version.
But, sadly, the new update was not reflected in any alias/shortcut for me (Moodle3.5.3).
I have to find one of the alisas and click on the 'Update' button, then all other alisas were updated, not too bad.
But, still, it will be good if this can be done automatically, I mean, whenever the original file was updated, a teacher doesn't have to find an alias and click the button to update it. Because, in most of the busy days, they tend to forget to do so. And they may not realize that their students still downloading the old version!