bbPress.org

Make a child theme of the bbpress first.

Then you need to edit the loop-single-topic.php file in your child theme to move the code below to replace the other code on the bottom..

		<?php do_action( 'bbp_theme_before_topic_meta' ); ?>

		<p class="bbp-topic-meta">

			<?php do_action( 'bbp_theme_before_topic_started_by' ); ?>

			<span class="bbp-topic-started-by"><?php printf( __( Started by: '%1$s', 'bbpress' ), bbp_get_topic_author_link( array( 'size' => '14' ) ) ); ?></span>

			<?php do_action( 'bbp_theme_after_topic_started_by' ); ?>

			<?php if ( !bbp_is_single_forum() || ( bbp_get_topic_forum_id() !== bbp_get_forum_id() ) ) : ?>

				<?php do_action( 'bbp_theme_before_topic_started_in' ); ?>

				<span class="bbp-topic-started-in"><?php printf( __( 'in: <a href="%1$s">%2$s</a>', 'bbpress' ), bbp_get_forum_permalink( bbp_get_topic_forum_id() ), bbp_get_forum_title( bbp_get_topic_forum_id() ) ); ?></span>

				<?php do_action( 'bbp_theme_after_topic_started_in' ); ?>

			<?php endif; ?>

		</p>

		<?php do_action( 'bbp_theme_after_topic_meta' ); ?>

replace the abvoe code with below code..

		<?php do_action( 'bbp_theme_before_topic_freshness_link' ); ?>

		<?php bbp_topic_freshness_link(); ?>

		<?php do_action( 'bbp_theme_after_topic_freshness_link' ); ?>

		<p class="bbp-topic-meta">

			<?php do_action( 'bbp_theme_before_topic_freshness_author' ); ?>

			<span class="bbp-topic-freshness-author"><?php bbp_author_link( array( 'post_id' => bbp_get_topic_last_active_id(), 'size' => 14 ) ); ?></span>

			<?php do_action( 'bbp_theme_after_topic_freshness_author' ); ?>

		</p>