Holding down the option key will involve the Startup Manager. If you hold down the control key before making your selection, then your selection will become the default. This works for both internally and externally installed operating systems.
If Windows on the external drive is the default and the external drive is not connected, then the firmware will ...
From this siteyou should do the following.
Make sure Bluetooth is on.
with both air pods in the charging case, open the lid and hold down the button on the back of the case.
The green light in the charging case turns white.
Go to the Bluetooth menu item and select air pods and hit connect.
Now air pods should show up in sound Systems Preference panel.
keystroke "120" is not the same as key code 120; the former taps the keys 1, 2, and 0.
I've had success with the following AppleScript, but you can also try key code 120 and key code 113.
tell application "System Events" to key code 144 using command down
Sounds like you have mixed up your Contrast settings. You can increased in System Preferences > Accessibility > Display > Enable Increase contrast. Make sure to set the display contrast slider to Normal.
I'm posting this three years late, but I still wanted to offer my experience, perhaps to people still scratching their heads because of this issue.
What I've experienced is not entirely identical to the OP's case, namely the machine of concern is a MacBook instead of an iMac. However, the symptoms were highly similar: the system was not under much load, ...