Text Header/Master Page

I'm designing a portfolio of my work. I've set up the file with single pages. Most of the pages have graphics of the work I've done. To introduce pages for pages with content from a specific client, however, I'd like to have a consistently designed section page.

All that I really need for this section page is a text header at the top of it.

I created a B Master with a text layer that contains the paragraph and character styles I want to use, arranged at the top of the page. I then applied the B Master to a section page so that I could quickly change the text to say "This work for Client X." Lo, the text was not editable, however, on the page to which the Master B was assigned.

Is there a way to add a boilerplate text header to a Master page, then assign that Master Page to a page and have the text editable on the new page?

Or do I have to copy and paste? Or detach the text frame from the Master B?

Thanks!