Topped tank with 2 gallons and cruising range wasn't reset after 3 fills since from low (>30 mi)

2012 Prius C Two owner here. I was leaving for a long road trip to Seattle from Portland and decided to top my tank up the final 2 gallons before leaving, ensuring 1 fill up for there and back. When I filled my tank with 2 gallons the cruising range didn't reset. I then let the car get down to less than 30 mi range (at least 3 times) and still it it goes back to the initial 365 it filled to when it didn't reset. I have taken it to two different Toyota Dealers to get this checked out. Neither had any idea what to do or why. I usually, even in winter, get a fill to 415. I have 15,000+ on her and had 13000 when I had this happen. Please help?

 

I'm getting better gas mileage. And it is Portland. Never ending rain. I've taken my car to the wilsonville , Beaverton and Rose Quarter dealerships. They can't help.

 

I'm getting better and it's always raining. I've taken it to 3 dealerships in the area. I was the first in Portland metro to buy a 2012. I was told by dealer. They were so helpful. Was buying remote via phone basically when at parents' in San Francisco. I was taken care of the most amazingly by the deanship's owner. Broadway was amazing. Got $5,000 off before student discount and some other perks because of this wonderful fact. It is audio my first car. I would have even bought her without a test drive. He had to convince me I really should even rent one for a week before deciding. I didn't and love her. I get 1,500 miles for $100 worth of gas ($3.40ish average)