Hi there @Contactadrian, welcome to our forum and thanks for your post.
I'm sorry to see you are having issues with setting your account up due to it not accepting the password. Just to confirm are you having this issue on any specific browser?
In regards to your installation date this isn't something that can be changed via the online account unfortunately. The best thing to do if you need to change this is give the pre installs team a call on 0800 052 1734.
Regards
Nathan