Struggling to work with 1d array from API to spreadsheet

Question

Code that I'm working with:

function BTC_1hour() {

  var url = '/api/v1/market/candles?type=1min&symbol=BTC-USDT&startAt=1566703297';
  
  var response = UrlFetchApp.fetch(url); // store API fetch in variable named response
  var JSONresponse = JSON.parse(response);
  var formatData = JSONresponse.data;

  for (var i = 0; i < formatData.length; i++)  
  { 
    for (var j =0; j < formatData[i].length; j++)
    var ss = SpreadsheetApp.getActiveSpreadsheet();
    var sheet = ss.getSheetByName('1h');
    sheet.getRange(1,1,formatData.length, formatData[0].length).setValues(formatData);
    Logger.log(formatData[i][j])
    {
    
    }
  }
  
   
}

output into Google Sheets:

enter image description here

I'm trying to figure out how to no longer get the data that prints in columns F and G as well as format the date in column A from Epoch in seconds to human readable format.