I'm not sure if I got your question right. In fact if you want that your text scrolls with the page, you take the simple center (the one you call middle-of-page-center). If, instead, you want, that your text sticks to the page with a fixed position regardless of scrolling, you take the top anchor.
The three top anchors work like that:
Hope that helps in your decision.
The left icon (6 dots) allows you, to pin element to a position relative to the browser window.
For example: Using the middle dot in the upper row will cause an element to stay visible at this position, even if you scroll your page up/downwards. You will see this, if your page is longer than the browser window.
The right pinning icon causes elements to stay at a fixed horizontal position of the page (not the browser window), what includes, that element, which use this pinning, are scrolling up/downwards together with your page.
Here some links, explaining this a little bit deeper:
This nice sample site visualizes the pinning options: http://winter-jam.businesscatalyst.com/pinning.html (scoll the page and resize the browser window.)
Here a short video explaining the differences:
And here some explanations of the Muse Product Msnager Dani Beaumont:
Be aware, that in the latest version of Muse pinning was modified, what means among others, the „3-dot-pinning“ is very often applied automatically and you won0t have to click onto a dot.
Thank you, these are both excellent in helping me understand. It's much appreciated.