Since this is a laptop (I assume), remove the power cord and the battery for a few minutes, just to make sure it's really shut off. Then reconnect both, depress power button and immediately and continuously tap the Setup key (to enter the BIOS). On your Acer, it's not the arrow keys but DEL or F1 or F10. You should be able to set Boot Order there. I think the other menu you see is located on the recovery partition.