Louise, exactly which version of Windows 10 and NVDA are you running?
To get the windows 10 version, press the windows key, type "winver" (without the quotes), and press enter.
For NVDA, press NVDA+n, h, a.
If you press NVDA+R three times quickly, NVDA will be reset to factory defaults. If you do that, and then look for One Core in the dropdown available from NVDA+ctrl+s, do you find it?