How You Can Add a Tester to Your Task
If you want to assign the Task to someone who is responsible for testing out whether the task had been carried out correctly, you can to that within each Task.
Open the Task you want to add a Tester to.
Click on +Add field in the top right corner.
Then, choose the Tester field.
The Tester option will appear at the bottom of the right list within the Task.
Here, click on the Profile icon to select the specific tester for your Task. Select the person you want the Tester to be. You can find it from the list, or search for the specific person by name at the top with the search bar. The Tester can be a person who has access to the Board the current Task is in. Note that you can only add 1 Tester to each Task.
Once ready with that, the Tester will appear in the Task on the right side.