Grosh crowd sources the location of stores, meaning it learns their location from where people mark groceries as bought. Grosh comes with a predefined list of the national store chains of your country, but you can also add your own store names.
Grosh will start prompting users for the stores name for a location when many people start shopping there. Once a store name is assigned to that location, the store name will start to appear in the title of the app when you are at the store.
If you are in a store that you previously have set the name for, and the app does not detect it, this is likely to be due to your phone GPS being inaccurate. Thus Grosh believes you are not in the shop, but try restarting the app before marking groceries as purchased – this will trigger activation of the GPS again (to save energy, Grosh does not active the GPS when starting the app if you have started purchasing items).