Display Posts Which Match Both Categories

Beaver Builder
1

How do you display posts that match BOTH categories?

Example:
I want to display posts for “Activities” in “Lahaina”
I don’t want to see all “Activities” and “Lahaina” posts,
only those that match both categories.

Seems intuitively obvious, but can’t figure it out.

Help and advise appreciated.

2

The default for WP_Query is OR so you need to use the built in filter to change that to AND
see Custom Query Categories - AND not OR