can i change soil ?

so ive been using muliti purpose soil, and im gettin real iron defficencisys .. so i belive ... due to the ph i guess soil PH 7+ . ive gone out and bought some soil for azeulaz plant or somthing . its for plants with a lower ph more ideal i guess. can i change the plants to the other soil without too much stress? will they be okay because there not gona last long where they are?

forgot to mention im only veggoing . one plant is bout 3 weeks . and two of them are 2 weeks old ..