There are times, particularly with enumerated attributes, when it is useful to be able to change the value of an attribute in many artifacts at the same time.
Mass edit is the way to do this.
In Artifact explorer, select all the artifacts that you want to change (the "Expand All" option is often useful here), then right-click "Mass Edit".
In the Mass Edit window, again select the artifacts that you want to change. Note that they must all be of the same artifact type for this to work. Then, right-click "Column Multi Edit", pick the name of the attribute you want to change, and then the new value.
Save, and all the artifacts are updated.
Note: If the arttribute is an enumeration, you get three options when choosing the new value.
The default is to add the new value to the enumeration if it is not already chosen so, for example, a value of "None" where they were all "E" will yield a result of "E","None"
The next, which is typically what you want, is to replace any existing values with the new value so, for example, a value of "None" where they were all "E" will yield a result of "None"
The final option is to remove the value if it is already chosen so, for example, a value of "E" where they were all "E","None" will yield a result of "None"