WooCommerce change number of columns in the frontpage

You didn’t say what snippets you’ve actually tried, but according to the docs, you can filter loop_shop_columns like so:

function wpa65503_woo_shop_columns( $columns ) {
    return 3;
}
add_filter( 'loop_shop_columns', 'wpa65503_woo_shop_columns' );

tested and working for me with Twenty Eleven theme.

EDIT – this is the particular line in the default content-product.php template file that makes the above filter work. you could just set it directly if you’re using a custom template file and don’t need it filterable:

// Store column count for displaying the grid
if ( empty( $woocommerce_loop['columns'] ) )
    $woocommerce_loop['columns'] = apply_filters( 'loop_shop_columns', 4 );