You have quite a lot of option

For a visual guide, you just run

openproject reconfigure

and when asked for the database setup change it to using an existing database and then provide the necessary information in the following steps.

You can also use

openproject config:get DATABASE_URL

to fetch the existing connection string, alter it and then use

openproject config:get DATABASE_URL=[altered string]

to set it again. You’ll have to run

service openproject restart

after that.

Thanks a lot!