Reverting files to older SU version

I have recently got rid of Windows as a system on my computer because of its slowness, bloated size and because I only use it for SU. Am now running Ubuntu - the speed! - and have Windows contained in VirtualBox.

SU 2017 is much more demanding of the graphics card and will not run in my virtual Windows. A note on the VB forums said that Trimble recognises this problem but does not intend to do anything about it.

Unfortunately my SU was updated to 2017 - which seems to be though it didn’t run any faster and actually degraded when trying to model small curved components - before the decision to dice Windows. 2016 works as well or better in my virtual Windows and I want to migrate all files back to that version.

But how? SU seems to have no backward compatibility whatsoever - a feature I have over the years found to be ever present in office type programs and in many CAD machines. Is there any way of saving a 2017 version file as a 2016 (- or even earlier as in many ways I would prefer to use SU 2015)?

Use the drop down menu in the save dialog to save as back to version 3 if you want.

Thanks. I don’t know how I missed that - probably by never having had to use it before, and then over-thinking the problem.