Apply filters to fields in a workspace to control which records appear in a workspace picklist.
From the main menu, go to Administration > System Configuration > Picklist Manager

In the Picklist Manager, find the Workspace Picklist you want to edit and click Edit in the Action column.
Click Add another filter.
In the Filter on drop-down, select the field you want to filter by.
In the Filter drop-down, choose the filter type (e.g., contains, starts with), and enter the value you want to match.
To apply additional filters, click Add another filter and repeat the steps above.

Click Save.