There are three places you can search in Power Apps (that I know of).
Tree view has a search function that lets you search for your controls by name. As far as I know, you have to click on this one to get here. It's more like a filter than a search..

The menu has a search tab where you can search the entire application (except for custom component properties). You can get to this with CTRL-F when you are not in the PowerFx formula editor.

It also has a replace feature that won't even search regular component properties at all. You can get to this with CTRL-H when you are not in the PowerFx formula editor.

and the third search is within the PowerFx formula editor. It searches for text in the formula you are currently editing. You can get to this by pressing CTRL-F while editing a formula in the PowerFx formula editor.

It also has a replace feature. You can get to it by pressing CTRL-H while editing a formula in the PowerFx formula editor. (or by clicking the chevron to the left)

Do you know of another way to search in Power Apps?