PowerShell Winforms Textbox updates on other input but overwriteable - winforms

Question

Afternoon all,
I wanna believe this one is pretty easy but hitting a wall and can't figure out why.
I have a PowerShell winform that's going to create a new user account from a template. One of the fields I'm working on now is the line manager; once a template account has been found, auto-fill the line manager field, but allow it to be overwritten if this is incorrect.
For the pre-populated stuff I've been using:
$FORMCONTROL.Add_TextChanged( {
However once the template has been found and the line manager field written too, I can't overwrite it. Is there another Event I should be using to populate the box but allow me to delete the content and add something else?
The code below is a much cut down version of what I'm using. The functions allow for finding a user account and populating the ReadOnly box.
Function FindUser {
IF ( $SEARCHUSER -like $NULL -or $SEARCHUSER -like " *" )
{ }
ELSEIF ( $ACCOUNT = dsquery user -samid $SEARCHUSER )
{ $ACCOUNT = Get-ADUser $SEARCHUSER -Property * }
ELSEIF ( $ACCOUNT = Get-ADUser -Filter { mail -eq $SEARCHUSER } -ea sil )
{ $ACCOUNT = Get-ADUser -Filter { mail -eq $SEARCHUSER } -Property * }
ELSEIF ( dsquery user -name $SEARCHUSER )
{ $ACCOUNT = Get-ADUser -Filter { name -eq $SEARCHUSER } -Property * }
ELSE
{ $( foreach ( $SEARCHUSER in ( Get-ADUser -Filter { ( Surname -like $SEARCHUSER ) -and ( Enabled -eq $TRUE )
} -Properties Mail, Department, Office | sort Name ) )
{ $SEARCHUSER | Select Name, #{ N = "Username" ; E = { $_.SamAccountName } }, Mail, Department, Office
} ) | Out-GridView -Title 'Select the user account' -OutputMode Single | %{
TRY
{ $ACCOUNT = Get-ADUser $_.UserName -Property * }
CATCH
{ } } }
IF ( ( $ACCOUNT.SamAccountName ).count -eq 1 )
{ $Script:ACCOUNT = $ACCOUNT }
ELSE
{ $Script:ACCOUNT = $NULL } }
Function TemplateUser {
IF ( $ACCOUNT -ne $NULL )
{ $TAB1TEMPLATE_5.Text = ( $ACCOUNT.Name ) }
ELSEIF ( $TAB1TEMPLATE_3.Text.Length -lt 4 )
{ $TAB1TEMPLATE_5.Text = $NULL } }
# Creates the parent form and controls
$SDC = New-Object System.Windows.Forms.Form
$SDC.Location = New-Object System.Drawing.Size( 270,175 )
$SDC.Size = New-Object System.Drawing.Size( 900,600 )
$SDC.StartPosition = "CenterScreen"
$SDC.BackColor = "Lavender"
$SDC.Font = "Calibri, 8.5"
$SDC.FormBorderStyle = "Fixed3D"
#Tab 1 Template Account Label
$TAB1TEMPLATE_2 = New-Object System.Windows.Forms.Label
$TAB1TEMPLATE_2.Location = '35,90'
$TAB1TEMPLATE_2.Size = '200,20'
$TAB1TEMPLATE_2.Font = New-Object System.Drawing.Font( "Calibri",10,[System.Drawing.FontStyle]::Bold )
$TAB1TEMPLATE_2.Text = "Who are we using as a template?"
$SDC.Controls.Add( $TAB1TEMPLATE_2 )
#Tab 1 Template Textbox
$TAB1TEMPLATE_3 = New-Object System.Windows.Forms.TextBox
$TAB1TEMPLATE_3.Location = '20,115'
$TAB1TEMPLATE_3.Size = '200,20'
$TAB1TEMPLATE_3.Font = New-Object System.Drawing.Font( "Calibri",9 )
$SDC.Controls.Add( $TAB1TEMPLATE_3 )
#Tab 1 Template Textbox - When hit Return
$TAB1TEMPLATE_3.Add_KeyDown( {
IF ( $_.KeyCode -eq 'Enter' )
{ $SEARCHUSER = $TAB1TEMPLATE_3.Text ; FindUser ; TemplateUser } } )
#Tab 1 Template Account's Full Name
$TAB1TEMPLATE_5 = New-Object System.Windows.Forms.TextBox
$TAB1TEMPLATE_5.Location = '20,150'
$TAB1TEMPLATE_5.Size = '200,20'
$TAB1TEMPLATE_5.ReadOnly = $TRUE
$TAB1TEMPLATE_5.Font = New-Object System.Drawing.Font( "Calibri",9 )
$SDC.Controls.Add( $TAB1TEMPLATE_5 )
#Tab 1 Line Manager Label
$TAB1MANAGER_2 = New-Object System.Windows.Forms.Label
$TAB1MANAGER_2.Location = '35,400'
$TAB1MANAGER_2.Name = "Manager"
$TAB1MANAGER_2.Size = '245,20'
$TAB1MANAGER_2.Font = New-Object System.Drawing.Font( "Calibri",10,[System.Drawing.FontStyle]::Bold )
$TAB1MANAGER_2.Text = "Line Manager"
$SDC.Controls.Add( $TAB1MANAGER_2 )
#Tab 1 Line Manager Textbox
$TAB1MANAGER_3 = New-Object System.Windows.Forms.TextBox
$TAB1MANAGER_3.Location = '20,420'
$TAB1MANAGER_3.Size = '245,20'
$TAB1MANAGER_3.Name = "Manager"
$TAB1MANAGER_3.Font = New-Object System.Drawing.Font( "Calibri",9 )
$SDC.Controls.Add( $TAB1MANAGER_3 )
$TAB1MANAGER_3.Text = $( If ( $TAB1TEMPLATE_3.text -eq $NULL ) { "hi" } )
$SDC.ShowDialog()

Answer 1

I appear to have fixed it by editing the Function TemplateUser:
Function TemplateUser {
IF ( $ACCOUNT -ne $NULL )
{ $TAB1TEMPLATE_5.Text = ( $ACCOUNT.Name )
$TAB1MANAGER_3.Text = ( Get-ADUser $ACCOUNT.Manager ).Name
}
ELSEIF ( $TAB1TEMPLATE_3.Text.Length -lt 4 )
{ $TAB1TEMPLATE_5.Text = $NULL } }
Lord knows what I was doing wrong in the first place as didn't save the changes.
#TheIncorrigible1 - Curious to know what you mean by the formatting. Genuinely. Is there a more efficient way of writing? I'm aware that when complete this script is going to be pretty big so if I'm using unnecessary code I'm all ears.