Ok, so, i didnt really get the best answer ever, but i've got something for you. You adjust the PH by adjusting the water you water your plants with. Using ph down or up to get the ph of the water what you want, then you water. The only thing is, i don't know to what extent you need to adjust your PH. Also, if your soil is reading say, 5.5, it's probably 5.3-5.2. if it were 7, it would be slightly higher than usual.
so, get you some ph up, and adjust your water accordingly. Make sure you adjust slowly so your ph doesn't go crazy. Ph is touchy as balls. I'd check daily using runoff water from your pot or however you are checking your PH to monitor it's change all the way till 6.5-7. you want the color more green than yellow. Don't be too quick, plants don't like being above 7.