Your Tor Browser bookmarks should have one WeTheNorth entry. Not five. Not one per mirror.
The rule
Bookmark the mirror reference page on this Reading Room (or another source you trust to keep the signed rotation fresh). One entry. When you open it, you land on a page that lists the current mirrors. Copy from there.
Why not individual mirrors
Onion addresses rotate. A bookmark to an address the operator retired six months ago is a phishing risk if the retired address gets picked up by a clone (which happens often). Bookmarks to individual addresses go stale. Bookmarks to reference pages stay valid across rotations.
Where to store the bookmark
Inside Tor Browser only. Not in your normal browser. Not in a synced browser bookmark that lives on your host operating system. The bookmark belongs in the same isolated browser session where you actually use it.