There was a ‘Save Toolbar Position’ ‘Restore Toolbar Position’ menu item added in SU8.
This was introduce to help solve the toolbar mayhem that would occur whenever the window size was changed.
I believe it was removed when SU2013 was released as they had solved the toolbar issues.
It seems that with 2017 on some system you need to actually Save a file with your toolbar positions before they will fully stick. SU should remember the way you had things set up on the last instance closed, but if that doesn’t work try doing a Save as Template.