edit rss feed cache time

add_filter( 'wp_feed_cache_transient_lifetime', 'edit_chace_rss', 99, 2 );


function edit_chace_rss( $cache_time, $url ) {

    return 1 * HOUR_IN_SECONDS; /*chang the 1 (in hour) value as you want or you can change it to return 0 to disable the cache */
}