If I change the database user passwords (eventsentry_svc,

For the eventsentry_web account:
In the web reports menu, click Settings and choose Profiles, and type the new eventsentry_web password in the settings and click Test Connection. If the test is successful you can save the changes by scrolling to the bottom and clicking Submit. Repeat this for any additional web reports profiles that use the same database instance. You may need to restart the web reports to force all of the connections to restart and resume under the new password.

For the eventsentry_svc account
In the EventSentry console, scroll down the left side to the Actions section and then select your database, and then on the right side if you click the Create button in the upper right corner it will display the connection settings. Type the new password for the eventsentry_svc account and then click OK and then click the Test button to ensure that the new password is working, and save the new settings.

Modifying the eventsentry_svc password requires a restart of the EventSentry components. In the console you'll need to click Home > Services and then restart all of the listed services except for the web reports. If you do not use the Collector for your database, you'll also have to push the new settings to your agents (Groups > Push Configuration > Go) and then restart the agent services (Groups > Other Actions > Restart > Go). If you have manually installed the Network Services or Collector on additional remote machines, you'll have to log onto those machines and restart the "EventSentry Collector" or "EventSentry Network Services" service accordingly.

If you changed the password of the database administrator (postgres, sa, or mysql root) account:
The database administrator account is often used to automatically purge data from your database according to your retention requirements. In the EventSentry console: you can use the toolbar to click Tools > Embedded Scripts (Starting in version 4.2 this is under Home > Scripts > User Embedded). You might have a script called "auto_db_purge" or "purge_eventsentry_db" or similar, and you'll need to update the password in the script. You can verify that the script will work by accessing your purge schedule (usually under Packages > System Health > Database Purge) and double-clicking the schedule on the right and then clicking Test button in the schedule details.

In EventSentry 5.1 and later, the database purge can be configured to run from Web Reports. This purge will use the admin credentials saved in your Web Reports profile. To update them, open Web Reports to Settings > Profile Editor and update the postgres or sa password in the database admin settings. Then click the submit button at the bottom of the page to save your changes.