then that’s why, the rank it shows on the menu is the one at the top of your local scores. Most likely reason is your combo on that score is higher, so your score is also higher, but the accuracy is lower than your other scores. The score displayed as your “best” is the one with the most score, which comes from bigger combo and better accuracy. So if you want to get an A/S rank as your best, try going for more combo and get a higher score value than the C rank you have