Joseph- I’m sorry but you are incorrect here as well. It’s far from a rule across the board that you follow the minhag hamokom of a city you are visiting. A yid who is visiting eretz yisroel for yom tov still keeps two days of yom tov due to the minhag hamakom of where he lives. A woman from Meah Shearim visiting Brooklyn continues to wear her shawl even though it is not the minhag there. There are situations (such as in shul) where you’re mostly supposed to follow the minhag hamakom of the shul but please ask your LOR as to which minhagim should be applied when.
