Why do the satsumas on my tree never ripen
The first year the fruit was very orange, soft and sweet. Now they turn yellow but stay very hard and are extremely bitter.
When you say first year, I'm assuming that means the fruit that was on the tree when you bought it. If you give your tree the care it needs, and are patient, it should come around. Remember, it was removed from its nice cushy nursery to a big new world. It has to develop roots and do a bunch of growing. Other than youth, hard bitter fruit is most often caused by insufficient sun, environmental extremes, or water stress (too much then too little.) This article has more information: https://www.gardeningknowhow.com/edible/fruits/tangerine/mandarin-orange-tree-care.htm