the same does not happen when saved as a .xls file.
I’ve uploaded a demo xlsx file to my google drive, since I can’t upload it directly.
https://drive.google.com/file/d/0B9bRLhjnz_qsZ2RxRFYzX1A4cDA/view?usp=sharing
Adjust the page for a A4 print, save as xlsx and exit/close the program. Reopen and confirm if the adjustment is the same as previously saved.