Visitors online not working + URL change

[Soesoe]

Hello,

 

At this moment i'm trying to improve my website.

Now there are two things that I would like to have fixed:

 

1. The module 'Visitors online' doesn't work.

It shows there are 0 visitors online all the time

But in the statistics it shows correct visitors per day

The problem appeared after prestashop update

current version: 1.5.5.0

 

2. the url of my website now is for example: prestashop.com

I want to change it to www.prestashop.com

I can do this in the multistore option but many links then doesn't work.

For example: I can't login in 'my account' and CMS links give 404 error 'not found'

 

How can I change the URL and keep everything work correctly?

 

Thanks in advance for any help