In Rhino 5, the toolbars are stored in an external file with a rui extension. This is called a Rhino User Interface file. When Rhino installs it load toolbars in the default.rui file. Default.rui is located in the C:\Users\<user>\AppData\Roaming\McNeel\Rhinoceros\5.0\UI folder.
Sometime users report an edit they have made to their toolbars do not save. If you are having this issue, here are some suggestions to help you determine why it is not saving and how to get it saved.
Hopefully this will fix the your problem.
Tip: How to Reset the Toolbar Locations, if you are using Rhino 5 and the default.rui workspace, you can try running the ToolbarReset command.
Questions? Email Max Fugier.