Please help us help you and fill where relevant:
Your LimeSurvey version: Versión 2.72.5+171121
Own server or LimeSurvey hosting: Own server
Survey theme/template: Flat and modern
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Hello.
I am new in LimeSurvey so I need your help. 
I have just created a new survey with fields: name, lastname, etc.

In the other hand I have added some participants to my survey.

Now what I want is that when a participant logs in the survey (user has a password assigned), the field related, for example with name, gets filled with the name set for the partipant in the system.

For example the Name field should be filled automatically with the string NameUserTest that is the name of the user that is loged into the survey.

Is it possible to do that in LimeSurvey?. In case that it is possible. How can I do that? 
 

Versión 2.72.5+171121

First of all, this installation is now over 5 years old and hasn't received any update, bug or security fix for over 5 years. Considering that you are working with personal data here, I think it is important to update to the latest LS3 or better LS5 version.

Now to your question: From what I understand you have set the survey to closed / token based, you have created participants in the participants table (which you call users), they have a token (which you call password) and you have saved some fields like name, lastname, etc.

You want to pipe this information that is already available in the participant table into the survey, which is possible.

You should be able to pipe the stored data into the questionnaire e.g. as default answer by using something like {TOKEN:ATTRIBUTE1}, {TOKEN:LASTNAME}, {TOKEN:EMAIL} etc.

To add to Holch's comment - if the survey is non-anonymous, you don't need to load survey questions, you can download the token values with the survey data.

Thank you so much Holch for the information, I could solve my problem.

Thank you Tpartner for the infomation.