What you are describing is the current problem with the bing and yahoo engine. They don't give quality results for an unknown reason for some percentage of results. The reason why bing is the default on my instance is because it gives near limitless results as it doesn't rate limit. Before I had google enabled as default but it broke in early october (refer to this GitHub issue if you want to read up on it: https://github.com/searxng/searxng/issues/5286)
Either way since duckduckgo and brave also increased their bot detection the only "quality" general search engine left is presearch.
You can switch the engines when you go to preferences -> engines. There you can enable/disable engines however you want.
Hope this helps and thanks for your feedback!
