My site and plugins dont use protected content plugin register page as the register page?

Hi registration on my site doesn't seem to be working properly.

My subsite have standard memberships, where as my main site has a default membership. The reason for this is that when they click on links on the subsite they can access the protected content on the main site that is for all sites not just that one site, such as the job board as it recognises they are logged in

1. When someone selects a membership for example on ttia.networkassocation.co.uk, once they have clicked on register my account it allows them to view protected content before paying. I have set up two memberships with ticked and unticked in the "Allow users to register for this membership" box but this has had no effect. Customers need to pay before being classed as logged in and able to view protected content.

2. If a user is logged out and they click on my listing (www.networkassociation.co.uk) it allows them to register without choosing a membership, I know I only have the default membership set up on this site but shouldn't it be using the protected content plugin register page instead of bypassing memberships? Screenshot 1 is attached.

3. If someone clicks on a protected page like forum (www.networkassociation.co.uk) it shows the page shown in screenshot 4 but for some reason it adds "?step=register" to the URL when they click on register this adds sign up boxes to the page as shown in screenshot 2. This option shouldn't be there as they should only be able to choose subscription if there was some there. I don't want people to be able to sign up on this main site.

4. If someone chooses im attending in events (www.networkassociation.co.uk) it redirects them to screenshot 3 instead of the protected content plugin register page, however when you click on register it does and is laid out correctly without the extra ?step=register

Thank you for all your help