Issues with settings when creating VM on virtual box, and unable to install RHEL

[Pingpongofkingkong]

I installed VirtualBox Version 5.2.8, but I found a few issues below:

1) only 32-bit is available when Liniux is selected, 64 bit is NOT available.
2) Processor(s): only one can be set, even there are 8 cpus available.

Therefore, when I tred to install RHEL, I cannot see the first screen prompting installation.

Host: Windows 7

[Martin]

Please check I have a 64bit host, but can't install 64bit guests