hi Victoria

This can be controlled through the config.db file that comes with Totara - if you add the following line to this file 

$CFG->defaultblocks_override = ''name of blocks '';

To see other settings that can be added look at the file config-dist.php file below for an explanation of settings 

// These variables define DEFAULT block variables for new courses

// If this one is set it overrides all others and is the only one used.

//      $CFG->defaultblocks_override = 'participants,activity_modules,search_forums,course_list:news_items,calendar_upcoming,recent_activity';

//

// These variables define the specific settings for defined course formats.

// They override any settings defined in the formats own config file.

//      $CFG->defaultblocks_site = 'site_main_menu,course_list:course_summary,calendar_month';

//      $CFG->defaultblocks_social = 'participants,search_forums,calendar_month,calendar_upcoming,social_activities,recent_activity,course_list';

//      $CFG->defaultblocks_topics = 'participants,activity_modules,search_forums,course_list:news_items,calendar_upcoming,recent_activity';

//      $CFG->defaultblocks_weeks = 'participants,activity_modules,search_forums,course_list:news_items,calendar_upcoming,recent_activity';

//

// These blocks are used when no other default setting is found.

//      $CFG->defaultblocks = 'participants,activity_modules,search_forums,course_list:news_items,calendar_upcoming,recent_activity';

Regards