in bios check for system default settings or something like that ,iit usually the second one down the liast on the left side if there is two sides .you use the arrow keys to navagate around then hit enter ,then usually the + and - keys to change it ,then you save changes and exit

Manic, it would help to know the bios type on the machine in question but you are in the right spot.
Some will list ide0, floppy, CD etc in a list one below the other and you press the + or - to move them up or down in priority.
Others you change using the pg dn or pg up key
You are almost there... dont give up yet..

On some older systems there is a ssetting whereby you choose from a list of possible combinations, and it's usually called 'Boot order'.

On most recent systems, in an 'Advanced' menu in BIOS setup, you specify the device for:
1st boot device
2nd boot device.......

and so on.

Some systems, of course, may have it elsewhere in the menu system.

Make/model of your computer please, or preferably make/model of the motherboard.