BuddyPress.org

Requires some CSS knowledge.

You can probably override this setting in your child theme’s stylesheet (I’m assuming you already use a child theme!).

Don’t know what a child theme is?

https://codex.buddypress.org/how-to-guides/building-a-buddypress-child-theme/

When you’ve created a child theme, add this to your child theme’s stylesheet:

#wp-admin-bar {bottom:0 !important;}

#wp-admin-bar ul li ul {bottom:23px !important;}