The Instant Replace command in the Search menu allows you to instantly replace all occurrences of a word or of part of a line simply by editing one of those occurrences. The Instant Replace command ignores all settings on the search toolbar. The instant search commands have their own Instant Search Options.
Instant Replace can work in two ways. If there is no selection, or if the selection does not span multiple lines, then Instant Replace highlights all occurrences of the selected text or of the word under the cursor throughout the file. If you turn on the “double-clicking a word instantly highlights all occurrences of that word” search preference, then double-clicking a word activates Instant Replace for that word throughout the file. Nothing happens if the word you try to activate Instant Replace on occurs only once in the file. While Instant Replace is active, editing the occurrence under the cursor edits all other occurrences in the file. If selections are not persistent, moving the cursor away from the occurrence under the cursor immediately ends Instant Replace. If selections are persistent, instant replace ends when you make a new selection or you make an edit outside any highlighted occurrences.
The other way to use Instant Replace is to make a multi-line selection before invoking Instant Replace. Then Instant Replace highlights all occurrences of the word under the cursor within the selection. The selection is turned into the search range. Editing the word under the cursor edits all occurrences of that word within the search range. You can move the cursor to another word within the search to edit all occurrences of that word. You can make a selection within the search range to edit all occurrences of that selection. If selections are not persistent, moving the cursor outside of the search range immediately ends Instant Replace. If selections are persistent, making an edit outside any highlighted occurrences ends the Instant Replace. Making a selection outside the search range does not end Instant Replace when selections are persistent.
Only one search term can be highlighted at any time. Instant Replace turns off both Highlight All and Instant Highlight.
To change the color or underlining style used for highlighting search matches, customize the color palette and change the “Editor: Highlighted replacement” color. Change the “Editor: Search range” color to change the search range highlight.
Search|Instant Search Options