Reader Stephen Mette and his keyboard don’t see eye-to-eye about what should appear on his Mac’s display when he presses the quote key. He writes:
Whenever I type a single- or double-quote, it turns yellow. Whatever I type next, an alternate form for that character appears. For example, if I type a double-quote then the letter a, I get á; if I type a single-quote followed by C, I get Ç. To keep the quote mark as a quote, I have to tap the spacebar once, which removes the yellow shading on the quote, but doesn’t type a space. Then whatever I type next leaves the quote mark intact and places the following character normally. Any ideas?
What appears to be happening is that the Mac believes your single and double-quote keys are operating like the Option key. Normally, when you hold down Option and type the letter E, an underline appears with an accent over it. Then type a vowel and it will sport that accent—á, é, í, ó, and ú, for example. Hold down Shift-Option, type the letter C, and you get Ç.
So, something has changed the key assignments on your keyboard. I suspect that you’ve managed to change the keyboard used in the Input Sources tab within the Language & Text system preference. Open that Input Source tab and scan down the list of keyboard layouts. Anything in there checked that shouldn’t be? If so, uncheck it.
While you’re there, enable the Show Input Menu in Menu Bar option. This places a little flag in the menubar that indicates the keyboard layout you’re using. Should this problem crop up again, a quick glance in the menubar will tell you where you’ve gone wrong.