Let's focus on the Windows 7 that you upgraded to Windows 10. Till we know for sure that no malicious personal files were transferred over to it, it might be best to use a USB drive to transfer files for scan logs.
Please do as follows:
On the clean computer, Download McShield2 to your desktop and install with default settings.
In the control center, select scanner and check unhide items on flash drives
Anytime you plug in a USB drive, McShield will scan the device.
For the moment, plug your USB drive in and allow McShield to scan it. A log will be found in the following location:
C:\Program Files (x86)\MCShield (folder) > MCShieldCC > logs > all scans
Please post the log.