You can set PDF preview as the default previewer in your SAP system. So, to do this, in transaction code SP01, click on any of the spool number and from the top menu, click Goto and choose PDF Preview.
Next, click on Extras and choose Save Settings. This will save and set the PDF Preview as default. You can do the same step (choose Standard Preview) if you want to revert to the Standard Previewer mode.
Reference
- SAP Note 1627996 – SAPScript: PDF Previewer as default
