New members getting a user to my main site.

When a new user joins my network (muliti site) and gets a site for some reason there user name is also in the main site as a user on there as well as an editor. When this happens i remove them right away but i have still not found away to stop this from happening. I have the plug in “Access manger” but have not made any major changes to my settings. I am using Clone Site as well and using the settings that have always been working.

Thanks in Advance