Cannot assign more than 3584 mb of ram for guest OS in VirtualBox

[Kashif Khan]

I am using Ubuntu 64 bit host operating system and have installed VirtualBox Version 5.1.8 r111374 (Qt5.5.1). I cannot create more than 3584 MB Ram for guest Operating System irrespective of which operating system and their versions. I have 16 GB ram in host operating system. How can I assign more than 3584 MB of ram to guest OS

[socratis]

Does this happen only during the creation phase of the VM?
Or does it also happen if you try to change the settings after the VM is created?
And do you mind running a couple of commands?

• VBoxManage list hostinfo
  VBoxManage showvminfo "Your_Virtual_Machine_Name"

[Kashif Khan]

I have observed only during creation. I have not yet created because of this limitation.

[socratis]

Ignore the maximum at creation. Create the VM.
And the 1st command didn't even require any VM.