WP Theme Options (Issue)

I am sorry if I have to solicit help with regards to wordpress theme but it seems a prevalent issue to several wordpress themes that I downloaded in Envato Elements, however, this particular theme is what I badly like that suits to my project. I’m kind of disappointed, I feel authors treated Elements like a dumping site of their outdated themes, and didn’t bother to somehow update them. I hope you can help me with these issues, even in this matter only. I tried to contact the LA Studio (the theme owner) but they’re not responding.

I downloaded this Oasis theme, but I noticed parts of theme option isn’t working like the Header:

Then I also have big problem with uniformity of the header layout itself; when I switch to another page, it shows different header layout.

Compare the two images: