User CP -> Edit Your Details -> MBTI Type
Most people will believe whatever you tell them your MBTI type is. Some variation of Forer effect, I suppose.
In my own experience, I consider the notion of type "changing" to be irrelevant. Given how MBTI isn't anything near an exact science, one can never know with absolute certainty what their type without disregarding information that disagrees with their position. In addition, confirmation bias occurs much more easily and more commonly in individuals that hold they are a certain MBTI type.
My personal response to this problem is weigh the likelihood of being any one type over another based on the data provided without committing to any single option. Presently, based on my data, INTP seems like my most likely type. New input to my model does not disprove the model. Rather, it allows for an expansion of the model due to the new chunk of data that can be incorporated. Even if I appear to be more ISTP-ish than in a previous timeframe, it is fully possible that I have been ignoring something for whatever reason.
In other words, adjust your type according to what you know. Whether this adjustment was merely "correcting" a mistyping or indicating a change in your type does not matter. At this point in the development MBTI theory, there is no way to know which of the above scenarios prevails. However, even without knowing, one can "change" their opinion on their MBTI type without knowing what caused it.