Having some problems with my pc which is affecting the performance of Cubase 9.5 so I want to reset Windows.
After the reset how should I reinstall cubase? Should I reinstall the original Cubase 9 from disk and then upgrade to 9.5 or can I just reinstall the 9.5 update from MySteinberg? 
Thanks
Download the Cubase 9.5 full installer from the Steinberg Download Assistant and install that.
Thank you Romantique Tp! 
I was having intermittent crashes which I could not pin down. So I uninstalled pro 9 and pro 9.5 completely. Then reinstalled just 9.5 from the full installer and all seems to be working smoothly. Did not fix the mixconsole history bug but the crashing seems to have stopped. Ymmv.
I also have pro 9 and 9.5 installed at the same time. I will try what you did first before completely resetting windows. Cheers! 
Just to add to what I did. And this is a on a fresh OS install BTW. After backing up my personal Cubase App settings and deleting Cubase I then went through the various Steinberg program folders (64bit and x86 and program data folders) and manually deleted anything that seemed solely cubase related before reinstalling Cubase 9.5 (just some files associated to my cubase profile etc…not much really that the uninstaller doesn’t remove and if you are unsure just leave it alone). Hope it works for you!