How to Print in A5 Size

I have tried that. In the demo printer it works when it prints to notepad but when actually printing the text just rolls over onto the line below and everything becomes a mess. It maintains its ‘receipt’ printer width when actually printing.

To prevent roll over I had to decrease the line character count but that leave me in my original problem whereby I have an A5 sheet with only a corner printed as a receipt. Any ideas on how to circumvent that?