The default settings of the plugin allow customers to leave rating-only reviews. It means that a customer can add a comment with their review but it is not mandatory.
The review form templates settings will apply only to new review forms created for review invitations sent after the settings were applied. Review forms that were created earlier will not be updated.
The basic review form templates have an option Comment Required that makes it mandatory for customers to write something in their reviews. This option is available on the Review Reminder tab of the plugin's settings in WordPress.
Minimum Length of Reviews
The Comment Required option makes it mandatory for customers to write something but it doesn't set any minimum length for reviews. So, customers can submit reviews with just one character. The advanced review form templates provide an additional setting for the minimum length of reviews (in characters).
You can use this setting to require customers not just to write something but also to guide them about the length of reviews that is expected while they are typing.
How to Enable Advanced Review Form Templates
Advanced review form templates can be enabled and set up in your dashboard at www.cusrev.com. Once enabled, the advance templates will override settings of the basic review form templates from the plugin's menu in WordPress. Here is a tutorial about setting up review form templates: How to Set Up Review Form Templates.
If you have any questions about the plugin, please don't hesitate to post them on our support forum or submit a ticket for our support team (available for customers with Pro licenses).