This video is an exaggeration of sorts but it gets the point across. At high altitude, doughs proof way too fast and the amount of yeast/starter needs to be reduced. https://www.youtube.com/watch?v=2mfcvllfsxQ
These videos brings making Sourdough Bread down to all levels! Google LifebyMikeG for a whole collection and downloads for free https://www.youtube.com/watch?v=zhd1eeoM2Vg https://www.youtube.com/watch?v=BJEHsvW2J6M
