Panasonic KX-P7500 Operating Instructions Manual page 32

Squeeze the back of the length guide and slide it to the desired paper size
3
until it clicks into place.
The paper sizes are indicated on the bottom of the cassette.
Lift the rear right guide and slide it to match the width of the paper.
4
Squeeze the width guide and slide it to the far right side of the cassette.
5
Length guide
Rear right guide
32
Setting up the Printer