Vantage Theme not updating upon editing Theme settings

I am new the WordPress and I just downloaded Vantage theme for my website.
However I am enable to save any new settings when I want to work on the Home page, especially:
1) Logo: Enable to save changes when I uploaded new Logo
2) Layout: upon clicking on “Enable” for REsponsive layout, it wont save
3) Home: I want to use my New Slider (using metaslider plugin) and switch off the Demo slider — unable to save
4) Navigation: Settings enable to save neither

It is like when ever I click “save settings” all the changes reverted back to default.

Anybody can help?
Thanks so much.