Are you using "Windows Services window" for changing the SQL Server Service Account?

If you are using the "Windows Services" window for changing the assigned account for SQL Server service, you may face some problems later. When required, we should use SQL Server Configuration Manager, instead Windows Services because the Configuration Manager performs required operations such as configuring SQL Server related configurations, re-generating Service Master Key and decrypts and encrypts all objects that had been encrypted by Service Master Key. If you do not use Configuration Manager, you need to execute ALTER SERVICE MASTER KEY statement manually for completing the operation.