Ok,
To help you, I have just created a pseudo model, with five diagrams.
After opening:
- print in PDF to have the witness.
- Move the diagram in the last position to the third position (by the up option on the diagram in the explorer).
- Print in PDF to have the second witness: you will see that the order of the diagrams has not changed.
- Save the modifications (if not yet done)
- Stop and restart startUML
- Print in PDF to have the final witness: the printing is finally correct.