Change order of media from descending to ascending

functions.php

<?php
if ( ! function_exists( 'rtmedia_change_order_by_asc_callback' ) ) {
	/**
	 * Change order of media from descending to ascending.
	 *
	 * This function changes the order by query string when
	 * media is uploaded from byssypress activity page or from uploader widget.
	 *
	 * @param string $qorderby order by query string
	 *
	 * @return string order by query string
	 */
	function rtmedia_change_order_by_asc_callback( $qorderby ) {

		// get the post array.
		$request = filter_input_array( INPUT_POST, FILTER_SANITIZE_STRING );

		// check if $request is array and it is set.
		if ( is_array( $request ) && isset( $request['action'] ) ) {

			$action = $request['action'];

			$attached_files = array();
			// check if attached files is present or not.
			if ( isset( $request['rtMedia_attached_files'] ) ) {
				$attached_files = $request['rtMedia_attached_files'];
			}

			// check if media is uploaded from buddypress activity page or from uploader widget.
			if ( 'wp_handle_upload' === $action || ( 'post_update' === $action && is_array( $attached_files ) && ! empty( $attached_files ) ) ) {

				// replace 'desc' at the end of the string with 'asc'.
				$qorderby = preg_replace( '/desc$/', 'asc', $qorderby );
				return $qorderby;
			}
		}

		return $qorderby;

	}
}
add_filter( 'rtmedia-model-order-by-query', 'rtmedia_change_order_by_asc_callback' );

Add this code in functions.php file of your theme