Document the difference between Retroactive updates versus Active updating

Although this is an old post, I came across it having the same question. Since I couldn't find the answer, I did a trial with both options. "Retroactive" will run through all the nodes and update the paths right after saving the field. "Active updating" will only update the path when the node is saved. So use retroactive if you want to update all paths immediately. Otherwise use "Active updating" for a more manual process where you have to update/save each node.

The above description is correct. I agree that it should be made clearer in the UI.

If you select "retroactive", the setting only applies on save (causing the updates to run). After the operation completes, and refreshing the page, the option won't be selected anymore. This is the correct behavior.

Here is my proposal for the field descriptions:

Retroactive update

Move and rename previously uploaded files. After saving the field settings, the paths of all previously uploaded files will be updated immediately. This will only occur once. So after the operation is done, this option will be disabled again.
Warning: This feature should only be used on developmental servers or with extreme caution.

Active updating

Actively move and rename previously uploaded files as required. If necessary, the paths of previously uploaded files are updated each time the entity they belong to gets saved.
Warning: This feature should only be used on developmental servers or with extreme caution.

Thanks