See Settings -> Spell check settings. There you can edit a list of words that are replaced automatically. What you see there is saved in the file autocorr.txt in the PSPad main folder. It might be easier to edit it manually in many cases.
Besides, AutoHotkey (viz http://www.autohotkey.com/ ) might be very helpful for you. A script like :O:;ife::if{ENTER}then{ENTER}else will do what you describe. I have an AutoHotkey script running all the time that auto-replaces some abbreviations with stock phrases I often use. -- <http://forum.pspad.com/read.php?2,34138,34156> PSPad freeware editor http://www.pspad.com
