Credit: Facebook.com

Last week Facebook launched a new setting that changed all users' default email addresses to [name]@facebook.com, so that messages would be forwarded to Facebook profile inboxes rather than their regular email addresses. The change aggravated many users, but now, to make matters worse, that change has affected the contacts and address book settings on some smartphones.

The switch has caused the email addresses of many to change on some users' phones. What that means is that some who have Facebook contact-sync enabled on Android, BlackBerry and iOS 6 devices have been emailing their contacts at their Facebook.com address rather than their usual email addresses. That in turn has caused important messages to be missed by recipients, since messages are going into other email folders.

After hearing numerous complaints, Facebook has attributed the problem to a bug in some of its apps and has issued a fix for it.

"For people on certain devices, a bug meant that the device was pulling the last email address added to the account rather than the primary email address, resulting in @facebook.com addresses being pulled," a Facebook spokesperson told ABC News. "We are in the process of fixing this issue and it will be resolved soon. After that, those specific devices should pull the correct addresses."

That fix, however, still won't change the fact that the visible email address now defaults to your @facebook.com address. You can still change that option in your profile settings by following the steps below.

1. Go to your profile page.

2. On your Timeline, you should see a button that says Update Info. Click that. (You can also click on the About page.)

3. On the Contact Info box, click Edit.

4. The first item will be Emails, and you should see a new @facebook.com email address. Move your mouse cursor over the symbol that looks like a No Smoking sign.

5. Click the down arrow and select "Hidden from Timeline." Here is where you can choose which email address you want to have on your profile. All users need a personal email address to sign up for a Facebook account, so your original email address should still be listed here. Just change the setting next to the email address you want to use for Facebook alerts and messages to "Show on Timeline," or the open circle symbol.

6. Click Save.