All search options are “And” , not “Or”. Selecting additional options will reduce the number of results (i.e. Aim 1 AND Aim 2, not Aim 1 OR Aim 2).
For a simple text search, start typing and posts containing that text in the title or body of the post will show. Text search does not search the metadata (check boxes).
Each search option will only show if there are posts with that option in the database.
The search results should update as you make your choices. If not, click the “Submit” button.