how can i change size of paper from LTR to A4

[mus2007eg]

my printer hp laser jet pro mfp m125a 

When I photograph any paper, it takes the size of the paper as a letter not A4  Which makes the paper not appear complete  

[Repairatrooper]

Ensure that the paper size on the printer itself is correct for the loaded media, you set this via the front control panel. If you can log into the embedded web server of the printer you can also check for a setting that will automatically substitute A4/letter and resize correctly. On your PC, make sure the paper sizes in the driver match what is actually loaded in the printer. Finally, if you are printing a PDF make sure that the select paper size by document settings is off, as this often creates issues when a 
PDF created in a geographic area that uses different paper sizes is printed.

[mus2007eg]

it print correctly but when i copy page size A4  it do that don't copy all page