New registrants automatically defaults to Wordpress Admin access - instead of the lower level option

I'm using Membership for a Boy Scout website, all levels are FREE. I'm using only 2 levels, MEMBERS and TROOP ADMIN. I’m having a challenge with the Registration Page functionality. http://www.RivieraScouting.org The Registration Page is functional, but does not function to my expectation. When a new subscriber elects to regsiter for the MEMBERS or TROOP ADMIN level, they are granted Wordpress ADMINISTRATOR access – the highest level access.

Can you suggest a way to remedy?