Hi Mohammed,
May 17, 2017 Skype for Business - Exchange needs your credentials issue. The workaround is to log out of SfB, delete the saved credentials (using the button on the sign in page). If you are running Skype for Business Server internally, then you might try turning off certificate authentication. That should prevent it from saving the cert credentials.
I'd like to confirm if the operating system and Office 2016 suites are the latest versions. You can open any Office 2016 application, such as Outlook 2016, to update the Office 2016 suits as the following steps: In Outlook 2016, navigate to FILE > Office Account > Update Options > Update now. Check if there is any improvement after upgrading.
If the Skype for Business is already the latest version, please close the Skype for Business client and navigate to the following folder on your PC (press Windows + R key, then type the following in the run window): %UserProfile%AppDataLocalMicrosoftOffice16.0Lync )
Then find the folder start with “*** Email address is removed for privacy ***”, delete the entire folder. Wait for a while, start Skye for Business and sign again to check if the issue persists.
If you are the admin of your organization, please refer to the solution mentioned in You’re repeatedly prompted for Exchange credentials after you sign in to Lync
If the troubleshooting steps above don’t help, I need to collect some details:
1. What the detailed version of Skype for Business?
2. Some screenshots about the symptom.
3. If you switch another Windows User Profile, does the issue persist?
4. Have your organization deployed a Lync server or in Skype for Business hybrid? (It may need the IT admin to answer)
Thanks,
Lance