I have a new iMac and now that I've updated one of my InDesign catalogs, it does not see my previous URL to 'update existing document' when publishing online.
This URL has been given out across the company. How do I insert the previous URL... I do not need a new one?
Are you referring to Publish Online? If so, make sure InDesign CC2015 is fully patched. You should be at CC2015.3.
Also make sure you’re logged into Creative Cloud using the same ID.