64bit Virtual Box will not install

[Dur]

I downloaded virtualbox-5.2_5.2.4-119785-Ubuntu-xenial_amd64.deb and installed it. However, I cannot install any 64 bit OS - Linux only shows 32 bit, Windows only shows 32 bit.
My processor is an AMD FX-8320x8; I am running Ubuntu 16.04 x86 (64bit).
I have installed Virtual box 5.1, 5.2.2, 5.2.4, all amd64 versions and no program will allow 64-bit installs.

I had virtual box 5.0 64-bit installed with 10 different Linux boxes (all 64 bit) and Windows 3.0, 3.1, 3.11, 95, 98, NT, 2000, Vista (64bit), 7 (64bit), 8 (64bit), and 10 (64bit).
I had to reinstall my system and lost all my boxes. Now, I am trying to reinstall, but I cannot get any 64 bit to work.
Can someone help me?
dur

Note: I am running 8 different computers in this corner, two across the room, and four in another room. I built all the desktops. I have 8 Linux machines, 4 Macs, and 2 Windows 10 boxes.

[socratis]

Please go thoroughly through the FAQ: I have a 64bit host, but can't install 64bit guests. It's more geared towards Win hosts, but you can get the idea...

[mpack]

It's more geared towards Win hosts

Actually it isn't, the FAQ applies to all hosts. It does have some tips on specific issues which arise a lot, and those of course tend to be on Windows hosts simply because of market share.