Unable to switch off forced sign on to all mettings

Hi all,

Sorry if this is easy, but I am unable to stop invitees to a meeting being forced to sign in. 

It used to be that I could send out an invite and someone could just click on the link and enter the waiting room.

I have carefully went through the help files and it seems this area in the image may be the problem but I am unable to make changes to it.

My meeting client are most frustrated and I am effectively unable to send zoom invites out now for fear of angry users at the other end.

Any help would be most appreciated!

Thanks in advance.