I have had difficulty with technical support from a VPN provider (PureVPN out of Hong Kong). The on-line chat support person had me try uninstalling their VPN client application, removing the program data for that application, and then downloading the application again and re-installing. At which point I seemed to be seeing a different user interface (UI) than the one he was talking about! He asked me to send him a screen shot of what I saw -- so I asked him how do I do that? At which point he seemed to give up and asked me to send an e-mail to their technical support address.
I did that. But meanwhile, how do I capture a screen shot under Windows 10?