1. Create a custom course block : http://support.vibethemes.com/solution/articles/1000165124-creating-custom-featured-block-style
Note the name of the block, in above example it is : custom_block
2. Copy the file : taxonomy-course-cat.php from the parent WPLMS theme into the child theme
3. Edit the taxonomy-course-cat.php
Locate the line :
echo '<div class="col-md-4 col-sm-6 clear3">'.thumbnail_generator($post,'course','3','0',true,true).'</div>';
and change it to :
echo '<div class="col-md-4 col-sm-6 clear3">'.thumbnail_generator($post,'custom_block','3','0',true,true).'</div>';
To change the number of courses in one row from 3 to 4 , use this :
echo '<div class="col-md-3 col-sm-6 clear4">'.thumbnail_generator($post,'course','4','0',true,true).'</div>';