My F&O environment asked me to log in every time to when I started debugging. I changed OfflineAuthenticationAdminEmail in DynamicsDevConfig.xml (at %USERPROFILE%\Documents\Visual Studio Dynamics 365), but I noticed that the value got overwritten every time when I started Visual Studio and opened an F&O project.
I tried changing the value in j:\AosService\PackagesLocalDirectory\bin\DynamicsDevConfig.xml, but it didn’t have any effect.
After some searching, I found that the value is copied from Provisioning.AdminPrincipalName in web.config (e.g. j:\AosService\WebRoot\web.config). Setting my account name there finally fixed the problem.