Dual Boot Guide – How to Dual Boot Ubuntu 12.04 and Windows 7

Find where the windows bootloader resides by mounting the efi partition:

sudo mount -t vfat /dev/sdx1 /mnt/efi/

And search for bootmgfw.efi. Then, find the UUID of the drive:

sudo grub-probe --target=fs_uuid /mnt/efi/EFI/Microsoft/Boot/bootmgfw.efi

Add this UUID to /etc/grub.d/40_custom:

menuentry "Windows x86_64 UEFI-GPT" {
    search --fs-uuid --no-floppy --set=root UUID
    chainloader (${root})/EFI/Microsoft/Boot/bootmgfw.efi
}

Finally run update-grub.

I am not an expert on this, but I have been messing with the boot order for a while, so telling from my some-what experience: So like the same way you get into UEFI settings, go to the BIOS settings (you can go to Advance Start-up, choose troubleshoot, advance options, then choose UEFI Firmware Settings - restart to get into it) [like you normally do]. After you get into the UEFI settings, you should see an option called BIOS settings or start up settings (some thing like that). Inside that, you should see an options that says Boot Priorities, Start-Up order (or something that means close to that). If you go into that subsection, you will be able to see which OS or devices have priorities over other installed OS(like Ubuntu)/devices(USB, DVD). In you case, probably Windows OS or UEFI is above Ubuntu OS. So change the order of it via the given control options to bring Ubuntu option above Windows.

These things differ for each manufacture, but the base operation is the same. If you give some more information about your computer's (that had Ubuntu installed) manufacture and/or model, I will try to be specific. [the mentioned above is for Dell Laptop]

Probably this video helps :)

Hope this information helps at least a little :)