By default, SQL Server 2016 is configured to store data and logs in
C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\DATA
and backups in
C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\Backup
We do not store data under Program Files. So we needed to reconfigure these settings. However, when I changed the default locations to
only my Backup setting was saved: on checking the stored configuration, the Data/Log settings had reverted to Program Files:
I tried this repeatedly with different folders, existing and non-existent, populated and empty, but the result was always the same: whatever default location I chose for Data and Log, it reverted to Program Files every time.
If you go straight back into the dialog, what it shows is misleading (a bug) as SSMS really has saved your new default locations for Data and Log. But at this time it only shows the correct value for Backup.
After restarting SQL Server, the correct values are shown for all three settings: