That would be through your SEO, or search engine optimisation. This is basically an algoritm that YouTube uses, if you didn't know to help promote / highlight channels, the higher you score the better your search rank would be.
While the haven't officially confirmed what ranks you higher, as it can be a culmination of loads of things, certain tips can be used to influence this for example : -
- Regular uploading can push your ranking higher as they see your channel as being more productive
- More views / social interactions
- Better / more searchable tags
- Higher watchtimes / more videos being watched
- Interactions in general around your channel, for example if they are coming to your channel directly