To change the Integration Services Catalog (SSISDB) database Master Key encryption password, run the following Transact-SQL statement:

USE [SSISDB];
GO
OPEN MASTER KEY DECRYPTION BY PASSWORD = N'[old_password]'; -- Password used when creating SSISDB
ALTER MASTER KEY REGENERATE WITH ENCRYPTION BY PASSWORD = N'[new_password]';
GO

In the above Transact-SQL fragment, we first open the Integration Services Catalog (SSISDB) database Master Key with the existing password, and then regenerated it with a new one.