First double click on the task group in which you would like to mass edit your tasks.
Once your are inside the detailed view of the task group, you can choose to mass edit all task settings by clicking the button on the top right hand corner which is highlighted yellow in the picture below.
This pop-up below will appear. You do not have to select or enter in anything for each box. Only select or enter a new value for whatever task setting you would like to mass-edit. For example, If you only entered in a new error delay, it would only mass edit each task within the task group to have the new error delay value.
Another way to mass edit all tasks quickly is by doing
ctrl/cmd + a followed by
ctrl/cmd + u.
Mass-updating only a few tasks is very similar to updating all tasks at once. In order to update a select few tasks, you need to hold
cmd and select each task you want to update.