Need editing in print format in purchase order

I want to add columns in print format in purchase order in end of the PO
Like. CHECKED BY, APPROVED BY, AND PREPARED BY.

how can i customize this?

Try creating new fields for the Purchase Order form , adding the new fields then add them to the format.

From the Desktop click Customization, Customize Form, enter Purchase Order and scroll down the field list and add Checked by etc.

On the Desktop search bar enter print format list and from the list choose a PO one to edit or create a new one with Purchase Order as the doctype. Click Edit, right, scrolll down to the bottom , Add a Section, click the gear icon to set the number of columns and drag and drop your Checked by etc into the section.

Create a PO and choose the new print format from the dropdown , upper left.

I have created this. Now, how to add field under the created by section like terms and conditions as mentioned in the image

It looks like you have created a Section. If you have created the Checked by fields you must drag and drop them into the section from the list of fields to the left.

i have created the fields and section but it is not showing in print format when i am going to print the purchase order.

Is there need to add any script.
i am also sharing the image of sections created and print format. Please have a look:

When you saved the print format, you used a new name.

Remember to select that from the dropdown from your print preview screen,

The field type should be Data. When I tried it as Text it did not appear on the print.