You can search for a word or a phrase in the source or target segments in the current file by clicking on the magnifying glass icon in crossView on the left-hand side of the screen. This search allows you to search in both source and target, but it does not allow you to do Search and Replace.
To do Search and Replace in the target, use the shortcut Ctrl + Shift + H. The good thing about this is that is shows you all the occurrences in a list of hyperlinks which take you to the location if you want to see it in the context. That means that you can check that it will replace all the relevant occurrences before doing it. If there are occurrences you don't want to replace, simply untick them in the window.
