Hello @Te Ara Paerangi Community !

You may use the "showcase" mode in the settings of the block in the Developer app. Then the discussion post without image will have the default blue thumb. How to do that (for example you want to change the view of New Discussions block in the Homepage):

1) In the Developer app go to the Pages->System->Homepage area.

2) Open the block settings.

3) Change the content of the Code field from this value:

array (

 'module' => 'bx_forum',

 'method' => 'browse_index',

 'params' => 

 array (

0=> false,

  1 => false,

  2 => true,

  3 => false,

 ),

to this one:

array (

 'module' => 'bx_forum',

 'method' => 'browse_index',

 'params' => 

 array (

  'unit_view' => 'showcase',

  1 => false,

  2 => true,

  3 => false,

 ),