Hello Ivan,
Yes, it's possible, do you have experience in coding?
1. Go to PHPMyAdmin >> Select your db >> Tab SQL
2. UPDATE `c2g2o_gridbox_pages` SET `theme`='17' WHERE `app_id` = 4;
Where
c2g2o - your Joomla db prefix
17 - theme ID
4 - App ID
Regards,
Artem, Balbooa.com