You can change your name every 30 days apart, So since you changed your name on 6/24/2019 @ 5:28:04 PM, you may not change it until 7/27/2019 @ 5:28:04 PM. WHICH has already passed, so you log into Minecraft.net go into profile go down to your name and hit (change) or log into Mojang and find the (change) as well. You can change it back to whatever

Well I mean my name on the site here