Following are correct steps for changing of the value for the variable:
1. Select Administration>Rules & Notifications>Manage Rules.
2. In the Manage Rules page, select the SharePlex Manager rule you want
3. Open the severity level at which you want to override the variable
4. Click the Severity Level Variables tab
5. Click any available you want to change
6 . In the Expression/Message field, change the text there
7. Click "Add" button, and then click "ok” when you prompted with “are sure you want to save this expression? Or "You already have the expression/message of the same name. Do you want to replace it?
8. Then click “save” button