Multi Domain Website Problem

Hi there

I’m trying to work out if this is a problem with WordPress or with the DNS settings.

The company I work for is rebranding and we are keeping the same website, just adding a different web domain. To keep old traffic we are also using the old web domain & a couple of others that have been purchased recently (5 in total). All the domains are running through the plugin Multi Domains with Analytics. As we are changing name I wanted to get the primary web domain switched to the new company website, which I asked the web host to do. (Before this I changed the web domain in General Settings to our new website)

The problem now is that the majority of the image content in the body of the website doesnt work. It also looks as if the primary web domain is still showing the old company name (it reverts to this if you type in the new website name, after it loads).

Can anyone advise where this problem may lie. Could it be in the DNS settings or in WordPress? I’ve signed into wordpress from home & can see the web domain in General Settings shows the old address, even though I changed it to the new domain earlier today.

Thanks for your help