Additional authentication is not needed because the user already authenticated at the same assurance level or higher Msg

HI I have integrated M0365. 

In the Outlook client when the user sign's out and sign in again - It is asking for 2fa. 

But if i close the application and re-open the application - It is not asking for 2fa in the client. 

Mode of integration is WS-FED

I checked in logs : 

Additional authentication is not needed because the user already authenticated at the same assurance level or higher 

What should I do so that it ask me everytime for MFA??