Try this: https://anspress.io/questions/question/change-default-cover-photos/

comments not work with the7 theme and I see this log: PHP Fatal error: Call to undefined function presscore_get_button_html() in /home/shivahos/domains/shivahost.net/public_html/wp-content/themes/dt-the7/functions.php on line 1141

A blank page is most of the times some php fatal error. I would take a wild guess that you have “out of memory” error. ENABLE WordPress debug and check.

Did you used [anspress] shortcode inside answer? Have you done any customization or overriding?

good job guys

Its not required to subscribe by default now. If any activity is made on question, question author will get notification for all. hence its not required to subscribe by default.

This will be fixed in upcoming release.