Am I doing this right? Data merge / template

I am working on putting a deck together with about 20 entries of identical data format. I am frustrated because some of the basic functions of Indesign I am hoping to use like a template that adjusts all pages when I change the parent do not seem to kick in, leaving me wondering if I am doing something wrong or if I have the wrong impression of the software.

For example, here is a parent layout I am working on:

 The behavior that I would expect is that I could create my twenty pages, place the text and media, and then dynamically update all pages by changing the parent.

This seems to at least work for the image frames, but when I adjust the text frames, nothing happens. I changed the font color from black to white in the parent template and nothing happened.

Thus, I have begun to rely on using data merge to populate my content given than I seemingly have to regenerate the entire document when I update the parent. However, my understanding is that is the basic concept of a parent in the first place, leaving me a little unsure about the correctness of my approach. 

I appreciate any insights and help.

Thanks