Use transaction SU3 - Maintain Own Data which is located on the SAP Menu under IRIS User Tools > Own Data. Click on the Defaults tab, change the Output Device to the desired printer, then click Save.
Tip: An IRIS printer or Local4 (LC4) is recommended for printing ledgers and other heavily formatted reports. An IRIS printer or PDF_Email (PDFE) is recommended for use in the Web SAPGui.
For additional assistance utilizing IRIS, please visit our instructional documents and videos on the IRIS Help website. You can also submit a help ticket online if you have additional questions.