When using the assertion test step you can highlight multiple verifications and select "Change Source and Property". After you make your changes and select OK only the first verification is updated. ...
Whenever you want to update any bulk changes which is common to all cases it's better to as find and replacement using XML project.
Steps.
1.Just open the soap ui /ready api project in notepad++.
2. do the find and replacement for particular value and save this as same XML .
3.Importit from ready api so that your time will be saved...
Try and let us know.