If you want to change things like your password, time, standard language etc. you can do that on the page Special:Preferences.
There are different tabs which include related preferences. Please remember you have to save your changes, if you don't do this there won't change anything. There's also an option to reset everything to the default setting you had when you joined Wikia. This can't be undone.
Here you can see your username, the user groups you belong to on the wiki, you can add your gender and you can change your password.
You can see here you're signature. If you want to add a custom one you can insert the page where you added the code for it.
You can here change the language you view wikis in, but remember you'll see also German and Spanish wikis in English if you set it to English. But you can change here also the date format, the time zone, the skin, the landing page and how many ads you'll see
Here you can see what your current email address is and if it's confirmed or not.
Follow Pages I...
Here you can change the settings when you'll automatically follow a page.
Email me when...
Here you can change for what things Wikia has to email you.
Message Wall and Forum
Here you can change how often you'll be emailed when users leave a message on a thread you follow or on your message wall.
Here can you change some specific setting.
Disable all emails
If you check the box displayed in this section you won't receive any emails from Wikia. This option also overrides all the other email options.
Wiki options. Email me when...
Here you can change the settings for when you'll be emailed when things happen on that wiki. Only administrators have this option.
On this tab you can change your editing experience, what font you want to use in the editor and how you can start editing a page.
Under the Hood
On this tab you can change the settings of viewing recent changes, logs and histories. But you can also change settings of following pages and some advanced display options.
You can connect here your Wikia account with Facebook.