I was 'secure in the belief/knowledge' that I had done all I could. [=I felt confident because I believed/knew that I had done all I could]
They are 'financially secure'. [=they have enough money to live on; they do not have to worry about money]
You can access your bank account online using a 'secure' [='secret'] password.
(..) forces rise against her from within and without. She refuses to leave until the freedom of the former slaves is secure." She sounds like quite a woman. And she's alone, under siege, no family to guide her (..)2015 TvShow: Game of Thrones Title: Kill the Boy Season: 5 Episode 5