Hey Dan,
You might need to add an editable area around your content to be able to make changes to it from within the Landing Page editor.
Depending on which version of the editor you're using, this could look a few ways. If you're using the "Free-Form" Landing Pages, you might need to include a class="mktoContent" to the outer-most element (wrapper). Here's some more info on that: Create a Free-form Landing Page Template - Marketo Docs - Product Documentation
If you're working with Guided Landing Pages, welcome to the future! There are more options for editable areas in the Guided environment, here's a link to some docs on setting that up: Create a Guided Landing Page Template - Marketo Docs - Product Documentation
... on a guided landing page ...
As an example, it might look something like this before you add the editable areas:
<div class="copyright"> © 2017 Company Name Inc. </div>
<div class="links"><a ...>Privacy Policy</a> | <a...>Terms of Service</a></div>
It might look something more like this after you add the editable areas:
<div class="mktoText copyright" id="edit_Copyright" mktoName="edit Copyright"> © 2017 Company Name Inc. </div>
<div class="mktoText links" id="edit_Links" mktoName="edit Footer Links"><a ...>Privacy Policy</a> | <a...>Terms of Service</a></div>
Hope this helps, if not, let me know which version you are using and if you can post a simplified version of your code, I'd be happy to help plug in the right pieces to get you moving.
Good luck!
-Dave
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