I created a new pattern brush in Illustrator cs6. It appears in the brush menu of the file I created the brush in, but it appears nowhere else. It isn't anywhere in the Adobe Illustrator CC 2017 file (under Program Files > Adobe) and it doesn't appear when I go to the brush libraries menu in Illustrator. I therefore can't access it on any other document. Is there somewhere else it's saved or is there a way I can directly save it into one of the brush folders?
You can go to the Panel menu and save this document as a Brush library. You can then access the library from the panel menu or the button on the bottom when you are in other documents.
If you want the brush library to appear in the "Open Brush Library" menu, save the file to /Applications/Adobe Illustrator XX/Presets/en_US/Brushes. If you want the brush library to appear in the "Open Brush Library/User Defined" submenu, save the file to ~/Library/Application Support/Adobe/Adobe Illustrator XX/en_US/Brushes.
That's for a Mac, anyway. Not sure about the Windows locations.
You can also save the file with the brush as an Illustrator file wherever you want and open it as a brush library by choosing from the Brush Library > Open Brush Library > Other Library and browse to the document that contains the brush..
None of these suggestions are helpful. Not one.
Did you try them?