Default setting for the category dropdown filter.

Hi,

I have a question with regards to the category dropdown filter.

In both cases
1) the category filter in the search bar
2) the category filter when you post your question

I'm unable to get the default setting on "select category" The "select category" is not a category itself, but merely a placeholder.
I would like that if a person enters the page that the filter is set to this option. How do I do that.

It is set like this for the "select post type" dropdown, so I assume it must be possible.

Thanks in advance.