I entered Thailand by air from Vietnam on Oct 10, 2109 so was due for a 90 day report at immigration on Jan 7 2019. I went to immigration on Jan 2, 2019 to do my 90 day report. I was given a slip which said I have to do another 90 day report again on April 1, 2019. I am questioning this because I thought the 90 days would begin again from the actual day I was supposed to report initially which would have been Jan 7, 2019, which going out 90 days would have meant I didn't have to report again to immigration until April 6, 2019. It might be moot since I am due to depart back to the US on April 1, 2019 so my 2 questions are should I have been give a new report date of April 6, 2016 based on the above scenario and secondly, since I am scheduled to depart from Chiang Mai back to the US on April 1, 2019 I am thinking that I wouldn't have to report on April 1 to immigration to do my 90 day report on April 1. Is that correct?

Your next report is 1st April.

You got the correct report date since immigration starts the 90 days on the date you do the report.

If you are leaving on April 1st there is no need to the report before leaving the country.