Startup disk ruined my booting setup

["Individual . ." <individual@mi-mail.cl>]

I had things set up quite nicely: turn on the power, and im presented 
with a black screen and "m for macos, l for linux". Defualt was macos 
after 10seconds. Or, I could hold down option key and get icons for 
the different OSs.

I opened the Startup Disk control pane, didnt touch anything, just 
opened it to have a look out of sheer boredom, and now it boots 
straight into macos, though the option key thing still works.

I tried running ybin, but it didnt change anything.

Suggestions?


PS. Thank you for replying to my previous posts, sorry for not 
thanking you personally (you know who you are!).