The SA password is established when installing SQL Server. For the SQL Server Standard and Enterprise Editions this password is created by your SQL Server database administrator within the SQL Server administration tools. The SA account password for a Blackbaud named Express instance that is installed with your Blackbaud software is proprietary.
If the SA password was changed on the SQL Server, then the workstations' settings must be updated to detect the change and properly connect to the database if SA is the account being used to connect. Refer to How to change the sa password used by each workstation to connect to the database (BB142472) to allow the workstations to connect properly.
Please contact the appropriate software vendor or IT professional for assistance with this process or issue, which is beyond Blackbaud's scope of support.