[Sonic Feathers]

Hey,
I've factory reset laptop now 4 times (last keeping all data on exHDD). Discovered that he/new data buyer was again in machine (thx to 2step Verification) & has again usurped UAC as 'Administrators' (I don't use groups, 1 person - me, is Administrator) after 1 1/2 years since my Android was stolen.
I've reset IP, changed passwords, stopped sync across devices etc. all to no avail. HJT Adspy doesn't pick up hidden data-stream, Combofix, Antihacker, Bitdefender, find nothing. Spybot at least advises me of another 'user'.This little pakistani man needs be stopped gaining access then I can ask how to reset UAC to default. The Android I believe had IEMI changed & is invisible, he's used Mac & Motorola initially but last access via iPhone. How is it possible to carry over what he needs, without my system disavowing the unknown electronic & denying access?
Help me understand please how he gains access? How can I terminate & block any attempt? How can I lock down UAC? I'll ask again later for help to get him out but definitely am through doing Factory Resets because of him. Thx