Bags Macs, Word and QuarkXpress are industry standards in publishing. I having been doing what I do for so long I am probably an industry standard by now as well.
What application are you using? If it's Word, then simply go into Word preferences and tell it what you want. Otherwise, I've never had a Mac do that – been using them since 1985 – so can't help. Sorry.
I hope some of you GN'rs out there can help me out? I've been given an Apple Mac which seems to be stuck on 'predictive text', and is driving me mad! I don't know how to come out of it. I'm a three year old technophobe when it comes to the internet and don't know what I'm doing:-( Is there anyone who could be patient enough to explain to me (in Noddy language') how I can actually start using my made up words without my computer telling me off and eliminating them???