If you're spiking too high soon after eating it, but BGs are where you want them 4-5 hours after bolusing, then the dose is probably ok but you may want to play with the timing. Try bolusing for the yogurt 10-15 minutes before eating it, or even 20-30 minutes if need be! (Experiment with shorter times first and if that doesn't work, try longer ones until you get something that works).
On the other hand, if BGs are not back where you want them 4-5 hours after bolusing (i.e. they go high and don't come back down) then it sounds like you need to take more insulin for the yogurt. The carb count you're using to work out your bolus may not be accurate, your I:C ratio may be off, or you may simply need more insulin for yogurt than for other foods (some foods have that effect on people!)
Worth mentioning too that it isn't as if "oh everyone can eat every food they want with no consequences, they just have to find the right dosing scheme for it!" Some foods just WILL cause higher BGs, search what you do about it. Or what you have to do to keep BGs in range while eating them is such a lot of work and hassle that it isn't worth it to you. In that case you have to decide for yourself whether to avoid or minimize how much you eat that food, or whether to accept slightly higher BGs if the payoff is that you get to eat foods that you want!