With ezmlm-make(1) (from ezmlm-idx >=0.21) you can use the -e switch to edit existing lists. Invoke the ezmlm-make(1) command just as you would to create the list anew, but change the switches to reflect the desired change, and add the -e switch. ezmlm-make will accept preexisting directories and overwrite or remove files to change the setup. The message counter (DIR/num), digest counters (DIR/dignum and DIR/digissue), the key (DIR/key) and the message archive will not be affected.
If the list has been created or previously edited with ezmlm-make(1) from ezmlm-idx>=0.23, the list remembers (via DIR/config) the arguments and the switches. All you have to do is to use the ezmlm-make(1) -+ switch and specify options you wish to change, or use the -e switch and specify all non-default options you'd like to use.
NOTE: ezmlm-make(1) -e and -+ will OVERWRITE any manual customizations you have made to the program files, but not text files and DIR/headeradd, DIR/headerremove, etc. To reset all such files (such as when changing list name), use -ee or -++.
To make general customizations, please change ezmlmrc(5) (see What is ezmlmrc? or read on) instead and use the -c switch as well. DO NOT use this option to change production lists without testing it on other lists first. Also, for some changes, removing or adding a flag is sufficient (see How do I quickly change the properties of my list?).