Hi there,
The easiest way I find to track participant information is through using an embedded data field and URL query string. First, I would create the following embedded data field on the very top of my survey flow:
Note that I left the embedded data field set to "Value will be set from Panel or URL".
Then, you can add a query string to your survey URL (https://www.qualtrics.com/support/survey-platform/survey-module/survey-flow/standard-elements/passing-information-through-query-strings/), which will provide Qualtrics with each participant's ID information. The URL that you would give to each participant would look something like so:

https://survey.qualtrics.com/jfe/form/SID=SV_1234?ID=12345

See that a query string is added to the end of the Qualtrics survey link--- you first add a question mark, followed by the embedded data field name (i.e. "ID" in this case), followed by an equals sign, followed by a given participant's ID.
You would update the ID number for each participant. When a given participant enters the survey, their ID that you gave them in their query string URL will be recorded by the embedded data field that you set in the survey flow. You would, of course, want to keep track of which codes you gave to which participants in a key somewhere.

Thanks a lot it solves my problem.

Glad it helps!!