notice how in key_1 audioFilePath = KeyStrings[0];

continue this logic/fix throughout the rest.

private void Key_1_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_1.ForeColor = Color.Red;
    audioFilePath = KeyStrings[0];
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_2_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_2.ForeColor = Color.Red;
    KeyStrings[1] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_3_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_3.ForeColor = Color.Red;
    KeyStrings[2] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_4_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_4.ForeColor = Color.Red;
    KeyStrings[3] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_5_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_5.ForeColor = Color.Red;
    KeyStrings[4] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_6_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_6.ForeColor = Color.Red;
    KeyStrings[5] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_7_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_7.ForeColor = Color.Red;
    KeyStrings[6] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_8_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_8.ForeColor = Color.Red;
    KeyStrings[7] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_9_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_9.ForeColor = Color.Red;
    KeyStrings[8] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_10_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_10.ForeColor = Color.Red;
    KeyStrings[9] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_11_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_11.ForeColor = Color.Red;
    KeyStrings[10] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_12_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_12.ForeColor = Color.Red;
    KeyStrings[11] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_13_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_13.ForeColor = Color.Red;
    KeyStrings[12] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_14_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_14.ForeColor = Color.Red;
    KeyStrings[13] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_15_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_15.ForeColor = Color.Red;
    KeyStrings[14] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_16_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_16.ForeColor = Color.Red;
    KeyStrings[15] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}
private void Key_17_Click(object sender, EventArgs e)
{
    duration = GetWaveFileDuration(audioFilePath);
    Key_17.ForeColor = Color.Red;
    KeyStrings[16] = audioFilePath;
    PlayWavFile(@"C:\Users\DjZaN\OneDrive\Desktop\Digital_Breath\Content\SFX\Click.wav");
}