External drive problem.

My existing external drive is no longer fit for purpose - disk for cloning too small.

I have (had) a media player for which I had no use but it has a 1Tb hard disk which seemed to offer itself for formatting and partitioning.

i went through the procedure, created 4 partitions, all formatted correctly, all seem to have the correct attribuites - GUID etc.,

Their icons appear under the volume name in Disk Utility.

Running "verify' on all resulted in "OK"

The icons also appear on the desktop.

So far so good.

They do NOT appear in the options for "startup disk" in System Preferences.

Neither do they come up as an option when restarting the computer with "alt" pressed.

I had intended as in my present EHD to reinstall a version of Mac OS on one drive and install my TechTool and DW there.

I also intended to use another large partition for Super Dooper cloning.

i had created 2 other small partitions, as I seem to remember reading that it gives more flexibility for moving things around.

I have a feeling that the solution will be evident to someone who partitions his/her disks fairly often and I would be grateful for any suggestions

Thank you.