Hi Amaya,
You need to activate the log for notes so that you can view the time and user details for each note entered.
To do this, in your text determination procedure, maintain the value P in "changes" column of the note type and also introduce note type "log" with 'changes' value as R. This will enable you to view the changes being done in notes. you can use note type "log" to view all these changes.
This is not related to CRM web UI. if the above settings are done, you will be able to view the details you are looking for.
Hope this helps.
Regards,
Divya