Windows 8.1 32-bit format to 64-bit

Hello, I am new to the forums :p I have a Bush windows 8.1 Tablet 32-bit with a 64-bit capable cpu, it has an intel Atom z3735g cpu, and the motherboard is bay trail, I do have a usb flash drive with 16gb (sandisk) and want to format to 64-bit and when I boot into bios which ever way it says usb boot not supported and I can't change boot from UEFI to CSM as there is no option I have used...