How to associate a PFX certificate from different identity (Windows-7) to upgraded computer (Windows-10) with new identity?

User upgraded to Windows-10 from Windows-7 created logon user identities are different from original. Encrypted data files were copied to new computer, but unable to access/open encrypted files. Installed .PFX and .CER objects from old PC to new one using certlm.msc. Still no joy! Assume the issue is different identities. Old identity is XXX-SSD while new identity is MySSD.  CER and PFX objects installed from flash drive.

Reviewing CertLM the certificates appear in following:
                CERTIFICATE           -                      Issued To             [Comments]
 Personal            -                                      MySSD                  [new identity]
Trusted Root Certification                              XXX-SSD                    [prior identity]
Intermediate Certification Authorities      XXX-SSD                    [prior identity]
Trusted People                                        MySSD                  [new identity]
Other People                                               MySSD                  [new identity]
Homegroup Machine Certificates  -            XXX-SURFACE
How do I associate the prior PFX with identity XXX-SSD to new identity MySSD?
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In short, you can't. A certificate, once installed, is unique to the SID of the computer and its OS. A new certificate must be installed.
wimbre042Author Commented:
For my own clarification. I have imported .pfx object from one OS upgrade to another before and had no difficulty with encryption. With the enhanced security of Windows-10 versus upgrade from Windows-7 I moved the Win-10 OS from HDD drive to SSD drive - The end result is I can no longer boot into the Win-7  OS to un-encrypt the files in that environment. To make matters worse, I changed the logon identity as defined in initial question.  Microsoft did not provide an adequate solution for those who wanted to install the new Win-10 OS on an SSD drive during the upgrade. Is there a way of recovering the win-7 boot to enable me to return to that OS to un-encrypt the files?
Aside from the security provided by the SID, Windows operating systems bind that SID to the specific OS being installed in addition to several major machine components, such as the motherboard, the processor and the hard drive. When you upgrade a computer from one OS to a later version, or in the case of Windows 7, or Vista reverting back to Vista or XP respectively, Windows rewrites the SID accordingly. Therefore, in the first instance you mention, you changed no physical aspects of the computer, merely its OS and thus had no problem. In the present case, you did two things at once, you moved the OS to an SSD drive and changed the identity.  Had you moved the Windows 7 OS to the SSD drive and then done an upgrade, you may have gotten away with it.  You may be able to re3cover some of the files on your Windows 7 drive by logging in as an administrator and then take ownership of that drive.

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wimbre042Author Commented:
Thanks for your comments - I now have a better understanding of the way I box myself in. Any suggestions on How to get a Dual Boot option which would enable me to boot into the Win-7 OS?
To be honest, I haven't yet tried to dual boot Windows 10 with any other OS. I am still trying to get past some of the worms that I have found. You might want to try setting up the dual boot on the Windows 7 drive and then point the secondary boot to Windows 10 on the SSD drive, but this is only speculation on my part.
wimbre042Author Commented:
I appreciate your input

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