I have seen a Macro with a command like "Prev_Channels" or "SET_CHAN_LEVEL" and wish to add it to a new Macro. Those commands are not options in the Macro Editor.
Description/Explanation of Issue
"Prev_Channels" and "SET_CHAN_LEVEL" are examples of internal commands used by Eos. These internal commands are used with encoder movements, color picker actions, and flash. These are all used when the command line is incomplete and Eos needs to restore the previous channels that were selected to the command line in order for your action to happen.
Not all commands that are used internally by Eos are available in the Macro Editor.
Generally, you do not need to add these internal commands to a macro. There are only a few very specific contexts where they may be needed - in which case, learning the Macro directly is the best solution, as the console will auto-insert those commands when needed.