Pin automatically removed?

I found weird stuff.

I pinned the topic on the top and I read it then the pin automatically unlocked, the topic not on the top anymore. (logged in as admin)

But the topic still pinned on top if I visit as non registered user and always stay on top no matter how many times I read the topic.

why is it like that?

Pinned topics get unpinned once they have been read. Anons don’t get read-tracking, because ain’t nobody got the DB space for that. So pinned topics never get marked as “read” by anons.

If you don’t want that behavior you can go to your
https://meta.discourse.org/my/preferences/interface
and uncheck the “Other - Automatically unpin topics when I reach the bottom.” option

that’s the option I was looking for but it only applies to my account?
how can I apply this setting to all the members?

There’s an automatically unpin topics option in your site settings

can you guide me in which section it exists?
I can’t find

/admin/site_settings/category/all_results?filter=unpin

But that only applies to new members who join, to update existing members you have to use a rake task and update their preferences.