I have a fresh install of 18.04 Ubuntu Mate 64 bit with the latest 64 bit virtual box (5.2.12) but when I try to create a new VM it only displays 32 bit options and will not allow 64 bit options.
This same machine 2 months ago using vanilla ubuntu 17.10, no problems, created 64 bit vms all the time.
I have uninstalled and re-installed VirtualBox 3 times from repositories and VB website to ensure 64 bit version.
Does your processor have Virtualization? I have 3 different generations of AMD processors, the old 939 pin AMD64 does not have virtualization so it only does VM’s in 32bit. Now my 965 Deneb core AMD3 has virtualization along with another AMD2. These have virtualization supported.
my cpu is a Intel core i7 -4700mq. When this pc had ubuntu 17.10 it worked fine… virtualization was working correctly. I will reboot and log into BIOS to make sure virtualization is still turned on.
I checked the BIOS and sure enough somehow it got changed back to having virulization turned off. Turned it back on and all options are there… Thanks!