Modifying rows in a table of a form in Service Catalog needs a click in a "edit" botton in 17.1 or newer earlier versions needed a double click.
Release : 17.X
Component : CA SERVICE CATALOG
Previously in Service Catalog 14.1 or earlier when ever a new row require edition a simple double click was enough to do this task.
Now in 17.1 or newer it is required to click on the edit botton to modify the value of the field.