When going from one page to the next through the page menu bar (located underneath the header), each time a new page is selected the vertical scroll bar returns to top of page i.e. header.

In other words, each time you want to look at a new page, you have to scroll back down again to the page text area.

Is it possible to configure the vertical scroll bar so that is does not automatically jump back to the top?

It's considered best practice to have important info at the top so you don't have to scroll. From what you are describing there is unimportant info at the top. I know of no way to have a page open partially scrolled.