How do I stop OS X from automatically inserting closing quotes?

Question

I have recently inherited a MacBook Pro from a colleague who has left the company. One of the annoying features that they had set up is that in every window/application that I can type the system will automatically try to enter closing quotes when ever I enter a single one.

I think the main problem is I don't know how it is supposed to work, as sometimes it adds it in, other times it does not. Either way, I hate it.

The way it appears is, as soon as you type the single character ', " or ~ (and probably multiple others) an underscore appears underneath it and I have to hit the space bar to accept the single version (did I mention it was annoying).

I've looked in the preferences and I can't see anything that could be causing this.

Answer 1

These are called deadkeys and used to enter diacritics to type ñ or é when followed by the proper letter (n or e in these cases). If you type a character that cannot be combined, it adds the character without combining it, as e.g. ~t.

Select a different keyboard layout in System Preferences » Language & Text » Input Sources, enable the Input menu and open the Keyboard Viewer to see which keys are set as deadkeys in your current keyboard layout (highlighted when you press the required modifier, e.g. Option):

Some keyboard layouts contain keys as both deadkey and regular character. The British keyboard layout for example has regular ~ next to left shift, and as deadkey on Option-N (shown in screenshot). The key next to left shift also has ` both as deadkey (when pressing Option, shown) and regular character without modifiers.

You can use Ukelele to edit keyboard layouts in OS X if there is no suitable one by default.