Make sure your theme is SEO optimized
- Is your theme mobile friendly?
- Is it clean coded?
- Is your speed fast enough?
- Make sure you have an SSL domain
- Are there any broken links?
- Is your content original?
Whenever choosing a theme new or old, you must make sure the above 6 questions are answered. If any of them do not work then your theme cannot be fully optimized leaving you off the top page of results.