Please bear in mind that the colonies of bacteria in our guts are fixed when we are babies and they can not be changed by adding new types of bacteria. They can be killed by the imprudent use of Antibiotics and gastroenteritis.
However, yogurt has a good effect on the gut while you are taking it and temporarily adds some good bacteria.
There is the impression that eating yogurt and drinking those little pots of probiotics can make a permanent change for the good to bacteria colonies. Unfortunately, as soon as you stop consuming it things go back to normal.