The app just opens your entire contacts list, it's a pain I know but I haven't found a way around it yet.
If you keep conversations with your most regular contacts on your phone at least you can just keep them going without going via contacts list.
I updated the firmware on my old Huawei Y300. It was quite straightforward and took about 10 mins. If you can find a firmware update I'd go for it, bear in mind it will wipe your phone so make sure you backup first.