[Blue Highway]

For example I'd want to set "when connected to power source" as powersave or whatever is the most energy efficient.

Turbo boost I want set to OFF

When on battery power I want the most efficient setting as well "powersave"?

How do I make these changes with the configuration using terminal?

[ProgressingAmerica]

Two things I didn’t more specifically mention:

The file may have permissions needed to edit it. You may have to issue a sudo command when opening the file. Some text editors are different. Sudo will bring in administrator permissions.

The command in terminal will look something like sudo gedit /etc/auto-cpufreq.conf

If the text editor can increase permissions (or no permissions are required) then nothing about this task requires the terminal. Just open the file make your changes save it and you’re done.