My PC update Windows 10 64 bit from Windows 7 32 bit.

My PC was preinstalled Windows7 32bit Home so it's not able to use over 3GB memory area. But now, Microsoft announced free updating for Windows10 then I try updating windows version with 64 bit system type.

I research version up route. Oh! It need clean install that'll all data and programs remove on my PS's HDD!! OK fine, I clean no valuable data and programs on my HDD.

Version up Overview:
   A. Save necessary files from current system(Windows7 32bit system).
   B. Make Windows 10 64 bit installing medium.
   C. Upgrade Windows 10 32 bit from Windows 7 32 bit.
   D. Clean install Windows 10 64 bit.
   E. Restore data from saving.

A. Save necessary files from HDD.

Pick up necessary files from HDD and save external media. When I don't use physical media, I save to cloud.

B. Make Windows 10 64 bit installing medium.

At first, "Download tool" download from Mictosoft site.

Next, Using "Download tool" download Windows 10 64 bit ISO image, and the image burn to your medium(ex. USB, DVD-R...). I burn to DVD-R cause My PC has a DVD drive.

C. Upgrade Windows 10 32 bit from Windows 7 32 bit.

Windows 10 32 bit update from Windows 7 32 bit before Windows 10 64 bit installing. This site isn't explanation upgrade, look Microsoft's site.

D. Clean install Windows 10 64 bit.
When Windows 10 32 bit upgrade successfully, the PC can upgrade Windows 10 64 bit. You confirm "Activate" installed Windows 10 32 bit in successfully.
Next, PC reboot and boot from Windows 10 64 bit medium(Step B. made).
Windows Setup Step:
   + First dialogue, Choice Language, Country and Keyboard.
   + Second dialogue, Click "Install now"
   + Activate dialogue, Choice "I don't have a product key"
I can install successfully up to steps.
How did PC activate  confirm? WinKey+x → "Control Panel" → "System". That's OK, Windows Activation show "Windows is Activated".

E. Restore data from saving.
Saved data restore by Step A and reinstall necessary applications.
If an application has 64 bit version, when installing 64 bit version.

Why don't installation directly Windows 10 64 bit from Windows 7 32 bit?
Windows 10 64 bit installer need 64 bit library when installing. But 64 bit library don't working 32 bit environment. However activated Windows 10 32 bit can clean install Windows 64 bit then installation has to "clean install".

Appendix.
My PC expand memory 3GB ----> 8GB!
Can upgrade Windows 10 64 bit Pro from Windows 7 32 bit Home?
   -> It can't install.