A miscreant could probably break into the admin account you set up for someone else easier than yours since your end user will probably create a weak password regardless of your advice.
Remember that you can change both the password and the name of your admin account. If you use a string that contains random letters, numbers, and punctuation for both, it would take someone years to break in that way given MODx’s lockout after n failed attempts.
Let me recommend Roboform here (
http://roboform.com), which will generate, save, and enter, relatively strong random passwords for you. I couldn’t live without it.
Bob