When a document is created for a Cabinet that has Jobs enabled, in the filing details in the Drawer, Job is included as an additional category. This displays all the jobs that are held for the selected client. If requried, you can also select to also show closed jobs.
Select the relevant job from the drop-down.
If a default job has been set for the selected client, this is offered as the default when selecting filing details, and can be changed if relevant. The default will also be automatically selected when documents and emails are auto-filed for the client.