how do you stop squeeking belts on a 98 mitsubishi mirage?

You change them, these belts are only good for 5 years at best. The rubber is getting old and brittle. You can already see the cracking on the ribbed side of the belt and becoming shiny on the back side of the belt. dressing the belt with a belt dressing or wd40 won't help you now--may allow the noise to go away for a day or two--but that's it.

tighten them up with just a very little bit (1/2 inch) of play and apply belt dressing.

Note; Some have suggested that you need to replace the belts, it may well need the belts replaced, but before I would go to that expense I would do as I have suggested above. There could be many reasons why the belt might be loose over the time it is possible that a bunch of different things could have been done and the belt never tighten properly to begin with, my solution cost nothing to try and if it works it will save you $$$$$$$$ if it doesn't work then you are out a few minutes of your time. Good luck

if its squeeking.. it means u need to get them changed.. plain and simple.. tighting it would just prolong the problem

change them now! procrastination often causes a domino effect with car parts

WD40 or change em..