I'm trying to disable autocompletion in login.fcc form by setting autocomplete attribute to "off" like this example:
<form action="" autocomplete="off"> First name:<input type="text" name="fname" ><br> Last name: <input type="text" name="lname" ><br> E-mail: <input type="email" name="email" ><br> <input type="submit"></form>
but is not working. This works fine in html5. Is there another way to do this in fcc page?
Default out of box Login.fcc does not have the exact coding section as you are using.
But check browser settings where "AutoComplete' was turned on, maybe can be turned off.
There are other 3rd party coding references on how to deal with this kind of situation, just list a few:
html - autocomplete = 'off' is not working on firefox - Stack Overflow
html - "AutoComplete=Off" not working on Google Chrome Browser - Stack Overflow
Disable Autocomplete: Turn Off Autocomplete in Web Forms