How do I find a distant relative IN MY TREE without checking lines from every individual?

PATRICIA7,154

Áine.ní.Donnghaile

If you know the name, you can use the FIND option.

https://www.familysearch.org/en/search/tree/name?from=tree

If it's a profile you have edited or worked on, you can find it in your Contributions.
https://www.familysearch.org/en/tree/contributions/changes