Hello,
I took the trouble to do a new WordPress installation and installed the free version of the “Roseta” theme you’re using.
It appears your issues are simply because you’ve not read the theme’s documentation, and you’re not using the theme as intended.
it seems the footer is one column
The theme has different content that goes into the footer: the copyright box, the footer menu, and even widgets. The Footer widgets area can be configured for 1, 2 or 3 columns… with the default being 2 columns. I suspect you’re not even using the Footer widgets at all — you’re trying to stuff everything into the tiny copyright box — that’s why you’re talking of the footer being only one column!
The tried to edit the theme option.. and it is visible,
Again, you’re not using the theme as intended. Instead of using the WordPress MENU system to create the menu and placing it in the Footer navigation location (as I mentioned above), you’re trying to type the menu links yourself into the copyright box. Of course, you can do this, but then if you’ll need to write the HTML code yourself to turn the text into clickable links!
Please spend some time and read the theme’s documentation, so you can easily configure it: https://www.cryoutcreations.eu/docs/themes/?theme=roseta
Good luck!