This small fix turns off the return of goods for all but logged users

By default Returns available for everyone in Opencart
for 15x - at link yoursite/index.php?route=account/return/insert
for 2x and 3x - at link yoursite/index.php?route=account/return/add

After applying this patch, the option to return the goods will only be available to logged-in users

Also can help avoid bots creating fake returns such as:
JimmiXzSq uAAigalmptCQMNJR
Barnypok BFdsIrXAeYr
etc

(But better way to avoid bots - is to use reCaptcha from Google)

FEATURES
✔ Compatible with Opencart 1.5x - 4x
✔ Does not change core files, works through VQMOD/OCMOD/Events
Requires VQMOD for 1.5x
Uses OCMOD for 2x-3x, and Events for 4x

Install 1.5x
Just copy file returns_only_logged.xml into folder vqmod/xml

Install 2x
1. Upload file returns_only_logged.ocmod.xml into Extension > Extension Installer
2. Refresh the modifications cache in Extension > Modifications

Install 3x
1. Upload archive returns_only_logged-3x.ocmod.zip into Extension > Installer
2. Refresh the modifications cache in Extension > Modifications
3. Refresh theme cache in Dashboard > Developer Settings

Install 4x
1. Upload archive alexdw_returns_only.ocmod.zip in Extensions > Extension Installer
2. In the same place, after the module appears in the list, click the Install button on it
3. Go to Extensions > Extensions > Modules and install module
4. Configure the module and save the settings

OTHER USEFUL MODS: