Change products per page

I am just trying to change the number of products per page.

I have looked online, and tried adding:

// Display 24 products per page. Goes in functions.php
add_filter( ‘loop_shop_per_page’, create_function( ‘$cols’, ‘return 24;’ ), 20 );

To my functions.php file.

And I have tried changing the ‘Blog pages to show at most’ value in the main Settings > Reading.

Also tried using a Products per Page plugin to force the issue.

None have worked, and the page are still showing 9 products per page (We’d like to show all products on a page):

https://www.lloydloomonline.com/product-category/armchairs/

Seems odd to be showing 9 per page with 4 columns, so I’m wondering if I maybe changed a setting ages ago – but if I did I can’t find it now.

Any suggestions how I can do this would be much appreciated.

Thanks.