Hello,
thank you for the screenshot. Most likely your A5 pages are landscape only because they are rotated (the page itself is portrait and has a rotation). The Pages per sheet tool then treats them as portrait pages and places them side by side on a sideways sheet, and after turning the sheet page 1 is at the bottom. We could reproduce this with such pages, it is a bug and we have passed it on to development.
Until then, with a current version of PDF24 Creator:
- In the PDF24 Toolbox open Pages per sheet, choose 2 pages per sheet and set Direction to RTL. Then page 1 comes first.
- If the sheet is shown sideways, turn it with Rotate PDF pages so that the text is upright.
The tool is also available online: https://tools.pdf24.org/en/pages-per-sheet
If the order is still wrong, please send us the two A5 files to forum@pdf24.org, so that we can reproduce it with your files.