Hello,
the current version is 11.31.1. Download it from https://tools.pdf24.org/en/creator and run the setup, it installs over your existing version.
Since version 11.31.0, the PDF24 Reader pages through the document page by page when the fit setting is Width + Height or Height: Page Up / Page Down and the mouse wheel move by exactly one page, so every page sits at the same place in the window. With Width or a free zoom level, Page Up / Page Down scroll by one window height, so the page border moves, as in continuous scrolling.
Please let us know whether this solves it for you.