Safari converts double quotes to special letters

Please read this whole message before doing anything.

This procedure is a test, not a solution. Don’t be disappointed when you find that nothing has changed after you complete it.

Step 1

The purpose of this step is to determine whether the problem is localized to your user account.

Enable guest logins* and log in as Guest. Don't use the Safari-only “Guest User” login created by “Find My Mac.”

While logged in as Guest, you won’t have access to any of your documents or settings. Applications will behave as if you were running them for the first time. Don’t be alarmed by this behavior; it’s normal. If you need any passwords or other personal data in order to complete the test, memorize, print, or write them down before you begin.

Test while logged in as Guest. Same problem?

After testing, log out of the guest account and, in your own account, disable it if you wish. Any files you created in the guest account will be deleted automatically when you log out of it.

*Note: If you’ve activated “Find My Mac” or FileVault, then you can’t enable the Guest account. The “Guest User” login created by “Find My Mac” is not the same. Create a new account in which to test, and delete it, including its home folder, after testing.

Step 2

The purpose of this step is to determine whether the problem is caused by third-party system modifications that load automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.

Please take this step regardless of the results of Step 1.

Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Start up in safe mode and log in to the account with the problem.

Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t do this. Ask for further instructions.

Safe mode is much slower to start up and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal startup may also be somewhat slow.

The login screen appears even if you usually log in automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.

Test while in safe mode. Same problem?

After testing, restart as usual (not in safe mode) and verify that you still have the problem. Post the results of Steps 1 and 2.

Under the Edit menu, please deselect all the options in the Spelling and Substitutions sub-menus. Test.

Please disable all Safari extensions and test. If the problem is resolved, re-enable the extensions one or a few at a time until you find the culprit.

Are any text replacements defined in the Keyboard preference pane?

The warranty entitles you to complimentary phone support for the first 90 days of ownership.

If you bought the product in the U.S. directly from Apple (not from a reseller), you have 14 days from the date of delivery in which to exchange or return it for a refund. In other countries, the return policy may be different. If you bought from a reseller, its return policy applies.

Pitiger wrote:

So "a gives ä. It should be possible to turn this feature off. But where?

Go to system preferences/keyboard/input sources and use the buttons there to Remove the item called US International PC.

(The US International PC keyboard is specifically designed to let you type accented characters by typing punctuation characters and then the base letter. It is often favored by people who have switched from Windows)