Seems like qt creator does not remember the position of the scrollbar if your last action before losing focus of the document was scrolling.

Steps to reproduce:
1. Open document long enough to be able to scroll.
2. Scroll to bottom of document
3. Lose focus of document (eg. by alt-tabbing or clicking on another open document.)
4. Observe that the scroll bar has reset back to the top of the document.

The current workaround is to click somewhere in the document after having scrolled. If you click on the document before losing focus of the document, then the scrollbar will not revert to its original position.