Songtrust is a publishing administration company. As publishing administrator, we're authorized to register your works and collect money on your behalf - you still own and control 100% of your copyright.
If you do have a publishing entity and you'd like to have it listed as your personal publisher information, you can include it when you add a songwriter. If you've forgotten to do this and you've already added your songwriter without publishing information, please send us a message on the chat box with your publisher name and IPI, and we can manually add it for you.
Once your personal publishing entity is listed on your Songtrust account, it will be listed as your publisher, with Songtrust listed under the contact info. This article gives an example of how that might look in your PRO.