Game never keeps me logged in

Hey so I’m newer here and to the game but when I go to the menu and hit the “Log In” button it’ll bring up a menu for blizzard and login using my email which is attached to my in game account, but then when I go back in the game it doesn’t seem to keep me logged in? It’ll just give me the option to sign up or log in every time even after I’ve logged in. Occasionally it still tells me to sign up to save my progress. What am I doing wrong? Is it a bug or is it the game? Any help would be greatly appreciated as I’d like my stuff to be safe and I’d hate to lose progress after playing a bunch. Thank you.