The only place I know of for setting a default channel and volume is in the “Power Timer” section of “System Settings”.
There is no “more” selection, but you get to it by going to “Power On Timer” then going right and selecting “Set Timer” where you can set a time as well as Ch and Volume.
It is fairly normal to have it set up to come on early in the morning (say 0700) and then set “Power Off Timer” to 0720. This gives the box a chance to refresh the EPG before you use it later in the day.