Thanks for asking.
Save Theme Options settings: You can save Theme Options settings from X > Validation > Theme Options Manager.
2. If you are making changes into theme files then in that case it's advisable to install and setup Child theme. You can use following resources to download and setup child theme.
Download Child theme from following source: https://theme.co/apex/child-themes
Please take a look at following article to setup child theme:
3. I also suggest you to learn more about Template manager. Here's resource that you can take a look.