In Visual Studio 2010 and earlier, the Find in Files feature remembered your selection for the "Look in" option.
In 2012, the option sometimes gets reset to "Current Document", making it only search in a single file. This can be annoying, particularly when you don't notice it's done it.
Is there any way I can force this setting to stick with what I want it to be (generally "Entire Solution")?
As an example of the problem, highlight a few lines of text in a source file and bring up the Find in Files box. It will have changed the "Look In" setting to "Selection". Close it, deselect the text and do Find in Files again. The setting will have silently reverted to "Current Document". Doing this in 2010 and earlier doesn't change the setting.
There's another description of the problem here.