Developed app & website... Need troubleshooting to fix a few errors!

I have a fully developed phone app (iPhone & Android) and a fully developed website. The website and phone app are tied in together on the back end. I am having a few errors occur that I need fixed. The code is not simple it is pretty complex. It is for restaurants. Each restaurant has their own admin panel to edit/add information. New restaurants can register. Restaurants can upload menus, etc. Here are a few of the troubles I am having: When an owner registers on the website, their username isn't working to login on the phone app. When an owner uploads a menu on the website, it doesn't show on the phone app. When an owner updates the "wait time" on the phone app, it doesn't show on the website. Right now, when a customer clicks "place order" on the phone app, the system crashes. There is a "0" displaying after the state on the restaurant profile page on the iphone app. I changed the logo that should appear when first opening the iphone app, but don't know how to replace it. looking forward to your bids! thanks.