How can I let more than one apply with my form from 1 computer?

If I understand your question correctly, you want to save your input data so another user can continue to fill your form. There are several ways to do that.

First of all, you can save input data in the session. Please, check the guide below for more information:

http://www.jotform.com/help/97-How-to-Save-Forms-to-Continue-Later

Alternatively, you can enable the "Auto Fill" feature of your form. At that situation, your input data will be saved in your browser cookie. You can see the following guide for more information:

http://www.jotform.com/help/227-How-to-Enable-Auto-Fill-Feature-Save-Form-Entries-to-Continue-Later

If you have any question or issues, please do not hesitate contacting us. We will be glad to assist you.

no
there are many users complain that they can't fill mor than one registration form from same computer
...

Your users can't submit on the same browser on the same computer because you have enabled the "Unique Submission" option in your "Preferences" as "Check cookies only". 

 

This means that users can only submit a form on a computer once, based on the current cookies the browser is using. If they need to submit the form again using the same browser, they need to clear their browser's cookies and cache. If you would like your users to submit the form multiple times on the same computer and browser without restriction, please set the "Unique Submission" to "No Check".

You can learn more about that feature on this guide: https://www.jotform.com/help/64-How-to-Set-Unique-Submissions-on-a-Form 

Let us know if this resolves your problem.