Keeping a panel undocked permanently

Hello Robbie etc.

Just writing to confirm that what you have descirbed is not typical behaviour - there is something going on with your system which is unusal and Peru Bob has outlined possible fixes.

Note also that there are issues with the design of Premiere Pro's handling of panel heirarchy (see here).

R.

You probably know this, but some users coming to read this won't. 

To make and save changes to a workspace means you would have to change this to a new custom, named workspace, as you can't save changes to the built-in workspaces.

Try resetting the preferences:
https://community.adobe.com/t5/premiere-pro/faq-how-to-reset-trash-preferences-in-premiere-pro/td-p/8236158?page=1

If that doesn't work, try resetting the Workspaces:
Reset a workspace
Reset the current workspace to return to its original, saved layout of panels.
1. Do one of the following:
• Click the Workspace menu icon and select Reset to Saved Layout.
• Choose Window > Workspace > Reset to Saved Layout.
from here:
https://helpx.adobe.com/premiere-pro/using/workspaces.html

If that doesn't work, try creating a new project and import the old one into it.