LowerCase and UpperCase

Hi can you help me change the uppercase letter to lowercase , I did change the code .toLower but still it change the answer only and not the random words generated

//add the correct char to the wordsArray
for (int i = 0; i < answerWord.Length; i++)
{

        wordsArray[i] = char.ToLower(answerWord[i]);
    }

    //add the dummy char to wordsArray
    for (int j = answerWord.Length; j < wordsArray.Length; j++)
    {
        wordsArray[j] = (char)UnityEngine.Random.Range(65, 90);
		
    }

    wordsArray = ShuffleList.ShuffleListItems<char>(wordsArray.ToList()).ToArray(); //Randomly Shuffle the words array

    //set the options words Text value
    for (int k = 0; k < optionsWordList.Length; k++)
    {
        optionsWordList[k].SetWord(wordsArray[k]);

    }

UnityEngine.Random.Range(65, 90);

The range 65-90 is uppercase.
Try using the lowercase range 97-122