SEO custom domain hosted on github-pages

Hi guys
I am trying to figure out why google ranks my page higher than my customdomain.
Actually I want google only to find my custom domain.
Another thing I am not understanding is why I can not find my webpage at all when using a different search engine like duckduckgo or bing.

My webpage is
Any suggestions are most welcome thank you very much!
Cheers grico

do you have a sitemap? that may help as long as the urls their are to your custom domain.

if it is a new site and you have not actually told DDG or Bing about it I would not expect it to just magically find it.

Thank you rdyar,
I am using jekyll-sitemap plugin and it is using my custom domain. I did not know I have to optimise my website for every single search-engine. I dig a bit deeper how to do that.

The main reason is that your domain is new, has no history and no links pointing to it, while is much older, features a huge amount of content and has an enormous number of links pointing to it.

The best thing to do is use the canonical HTML tag to explain to search engines that both feature the same content, but is the primary source. (See Google’s article - Use canonical URLs)

It’s impossible to answer why search engines aren’t displaying your results - there are hundreds of possible causes. To start with, you need to consider what keywords you are searching with.

If you want to take this area more seriously, you should register your site with Google’s Search Console and Bing’s Webmaster Tools.