Boot loader 15.3

My ThinkPad had been configured to have the boot loader on sda3.  In updating to 15.3, I accidentally put it on the master boot record on sda.  This has created a problem with updates to Windows 10, which I also have on that computer.  The major updates will choke if the computer doesn't boot from the Windows partition, so I'd use fdisk to change booting from sda3 to sda1.  It would then boot directly into Windows, allowing he update to continue.  After my mistake in updating, I can no longer do that.  I have used the Yast Boot Loader to move the boot loader to sda3, but the problem continues, no matter which partition I choose to boot from. Any idea how to fix this? tnx jk