Dual-boot straight to Windows 10 (MBR Legacy Bios)

I see lots of questions and answers regarding dual boot but all relating to UEFI...

I've just installed Ubuntu 20.04 over Win 10 with MBR partitioning and Legacy bios. (I've used Rufus to create installation with settings set accordingly).

I've tested Ubuntu and it worked okay, so I installed it. However, after restart it starts straight into Windows 10. I've disabled Hibernation and Fast-start but to no effect...

Is there any solution allowing to run Dual-Boot on Legacy Bios with MBR?

Thanks!

Legacy MBR boot should be using grub. When I've had problems with this in the past the best method for fixing it was to boot from the live media, in this case your USB media probably has this option, and then run Boot-Repair.

There are some instructions for using Boot-Repair here: https://help.ubuntu.com/community/Boot-Repair

There are also ways of repairing grub manually, but I think this is the direction you want to go.