Haechan did not partake in the single due to ongoing activities with NCT 127. The song was released as part of SM Station Season 3. In July 2019, NCT Dream was named as the first global ambassadors of the World Scout Foundation, with the group releasing the English-language single "Fireflies", the proceeds of which were used to fund Scout activities in low-income countries. The group also performed at the 24th World Scout Jamboree in West Virginia, United States on July 23. On July 26, NCT Dream released their third EP, "We Boom", and its title track, "Boom", marking their first comeback without Mark. The album became NCT Dream's best selling album up till then, selling more than 300,000 units after a month of release. It also debut on Billboard World albums chart at #7 and NCT Dream was at #3 on Billboard Social 50 Chart NCT Dream received two wins for "Boom" on "The Show" on August 6, 2019 and on August 20, 2019, respectively. "We Boom" later became the best selling album released by any NCT sub-unit up until and in the year of 2019.The EP also turned NCT Dream into one of the top 10 best physical sellers of South Korea in 2019 and earned them Bonsang Awards at the 34th Golden Disc Awards and 2020 Seoul Music Awards. On September 2019, NCT Dream was included in "Billboard"'s 21 Under 21 list for the second year in a row, being the first Asian artists to make the list for two consecutive years, this time rising to rank #13. In November 2019, the group featured on American-Canadian boy band PrettyMuch's "INTL:EP" with the song "Up To You", with lyrics praised for promoting consent. The group staged their first international concert tour, "The Dream Show", starting with three dates in Seoul and two dates in Bangkok from November to December 2019. On January 22, NCT Dream released a Japan-exclusive compilation album titled "The Dream", consisting of all previously released singles in their original Korean language. The album debuted atop the Oricon Albums Chart. In early 2020, NCT Dream continued with their international tour The Dream Show, with shows held in multiple locations in Japan as well as in South East Asia countries. From February 2020, several shows were cancelled due to the COVID-19 pandemic. As the topic of graduation gradually becomes more concerning since the prior year, on April 14, SM entertainment announced that NCT Dream will release their fourth Korean EP, "Reload" with the current six members Renjun, Jeno, Haechan, Jaemin, Chenle and Jisung to mark new change in their concept.