Currently, end-users are not able to edit the filters in Service Portal widgets. When the users expand the "My open incidents" widget, they get the default filter as -

All > Caller is User .or. Watch list CONTAINS ( User ) > Active = true.

But they do not have access to edit the filter instead they can edit the applied filter via the URL. How can we use to enable filter to perform condition builder?

Procedure

This is expected behavior in Service Portal widgets.

In Service Portal, "Data table from instance definition" widget to display the list of records.

The condition builder is only available for "Data Table from URL definition widget". The Data Table from URL definition widget displays the table you select from the list.

More info:

Data Table from URL definition widget

Data table from instance definition widget

Both "Data Table from URL definition widget" and "Data table from instance definition" embed the same widget "widget-data-table".

If you're using Data Table from Instance definition the filter has to be set in the widget instance options. You can make it work by passing 'enable_filter' as true. 

These Community conversations contain additional information:

• Add filter to service portal
• Condition builder in Service portal