It's been a year since I last played this game, so I don't know if you just changed it or not, but I need help with this. The Subeta wiki says that the quick stock option is supposed to be in the edit shop tabs, but it's not there! If anyone could please help me find the quick stock option in my store that would help a lot. Thank you!

are you trying to quick stock to an old shop? shops were recently moved to a new system, so you can no longer put items in your old shops. to quick stock, you would have to make a new shop. there's a topic here with more information about new shops - New Shop Guides

Oh, I didn't know shops had a new system now, I'll do what the guide says. Thank you!