Although displaying page breaks is a worksheet level property, it is a
setting that is not saved with the workbook. And when Excel opens a
workbook pagebreak display is always off.
So, as far as I know, the only way you could have it be set on when a
workbook opens is through a macro. If you haven't delved into macros before
this can be tough sledding, bit for what it's worth:
Running a macro in a specific workbook automatically is discussed here: