There may be some groups that you want new users automatically joined to, for example a space for announcements or a company blog.
If you have not already carried out secondary authentication (your name at the top will be in red if this is the case) then go to My preferences, choose the System administrator log on option and enter the password. Next, go to theBlogs, Monitors or Spaces section and locate the group. Select the dropdown menu button next to its name and choose the Edit option. Now on the form ensure that you have chosen Yes for the New user default setting and select the Save button.
Note that when a group is chosen as a new user default then any member workflow settings, such as having new members approved, will be ignored when the new user is made a member. The user will also not receive an email notification welcoming them to the group, to avoid them being inundated with email from all the groups the have been automatically joined to. Any extra instructions should instead be added to the new user email notification.