Hi aleimam
If you are a developer and know how WordPress works, you'll know that editing the plugin files directly is a very bad practice that should be avoided. Mainly because you'll lose all your customisations when you update the plugin.
Any customisation you need to do should be done using WP hooks.
Anyway, please do read this post where I explained how you could achieve this:
https://forum.stockmanagementlabs.com/d/2356-possibility-to-add-a-remark-column-in-the-action-logs
But please note that customisations like this are out of the scope of our support service. We can give you some tips like this but cannot tell you how to do it.
Best Regards,
Salva.