Fields management

Moreover, is it possible to rename menu such as "ticket" for example?

No screen customiozation cannot manage menu names.
This is done by Personalized translation plugin, when you can replace any caption in any language.

Hi i bought screen customization plug-in. is it normal that most of the field name cannot be updated (field is greyed in the plug in) ?

Yes, you cannot rename existing fields.
You can just name and rename your new fields.

Another question : i would like to put a default value on a reference field but it seems that it does not work. How to proceed ?

Have a look at user manual of plugin.
Take care "default" value is managed only on creation.
It is not a calculated value, unless you set the field as readonly

How to make a list I created, depending on the existing product list ? I want to make a link between module & product

You cannot.
Lists in the plugin are just lists of choice, they are not customisable objects.

Again, where can i get the list of existing list of value to be able to add one in some screen?

On Parameter > List of values, you'll see all the existing lists of values.