Trigger Now... button
Immediately triggers all the tasks specified in this trigger. Note If you click Trigger Now... for an Enabled trigger that does not have an assigned Execution User, the trigger will launch its task(s) under the context of the Enabled By user.
Optionally, you also can select to:
If you click Trigger Now... for a Disabled trigger that does not have an assigned Execution User, the trigger will launch its task(s) under the context of your user name and ID.
If you click Trigger Now... for an Enabled or Disabled trigger that has an assigned Execution User, the trigger will launch its task(s) under the context of the assigned Execution User.