I have this code for a spelling and grammar checker with issues

1. To capitalize, add the following line of code just before you copy your text to the clipboard (Uppercase Letter[^]) -

RichTextBox1.Text = Char.ToUpper(RichTextBox1.Text(0)) + RichTextBox1.Text.Substring(1)

2. To underline the errors, you need to modify your code that checks the spelling or grammar. Replace your lines that perform your spell or grammar check with the following code (ProofreadingErrors object (Word)[^]) -

Dim errors As Word.ProofreadingErrors
If blnSpellOnly Then
    errors = .SpellingErrors
Else
    errors = .GrammarErrors
End If

For Each errorRange As Word.Range In errors
    errorRange.Underline = Word.WdUnderline.wdUnderlineSingle
Next

Make sure to add a reference to Microsoft Word object library. To add the reference, go to 'Project', select 'References' and select 'Microsoft Word'.

3. To display your form on top of any other forms as topmost, add this line of code before calling your '.Show()' (How to keep a Form on top of others[^]) -

TopMost = True

Your combined code will then look like the following (I have not tested the code but the links supplied will be your guide) -

Private Sub SpellOrGrammarCheck(ByVal blnSpellOnly As Boolean)
    Try
        ' Create Word and temporary document objects.
        Dim objWord As Object
        Dim objTempDoc As Object

        ' Declare an IDataObject to hold the data returned from the 
        ' clipboard.
        Dim iData As IDataObject

        ' If there is no data to spell check, then exit sub here.
        If RichTextBox1.Text = "" Then
            Exit Sub
        End If

        objWord = New Word.Application()
        objTempDoc = objWord.Documents.Add
        objWord.Visible = True

        ' Position Word off the screen...this keeps Word invisible 
        ' throughout.
        objWord.WindowState = 0
        objWord.Top = -3000
        Me.Activate()

        ' Capitalize the first letter of the alphabet
        RichTextBox1.Text = Char.ToUpper(RichTextBox1.Text(0)) + RichTextBox1.Text.Substring(1)

        ' Copy the contents of the textbox to the clipboard
        Clipboard.SetDataObject(RichTextBox1.Text)

        ' With the temporary document, perform either a spell check or a 
        ' complete grammar check, based on user selection.
        With objTempDoc
            Dim unused9 = .Content.Paste()
            Dim unused8 = .Activate()

            ' Perform spell or grammar check and underline errors
            Dim errors As Word.ProofreadingErrors
            If blnSpellOnly Then
                errors = .SpellingErrors
            Else
                errors = .GrammarErrors
            End If

            For Each errorRange As Word.Range In errors
                errorRange.Underline = Word.WdUnderline.wdUnderlineSingle
            Next

            ' After the user has made changes, use the clipboard to
            ' transfer the contents back to the text box
            Dim unused5 = .Content.Copy()
            iData = Clipboard.GetDataObject
            If iData.GetDataPresent(DataFormats.Text) Then
                RichTextBox1.Text = CType(iData.GetData(DataFormats.Text), String)
            End If
            .Saved = True
            Dim unused4 = .Close()
        End With

        ' Set the form to topmost
        TopMost = True

        Show()

        Dim unused3 = objWord.Quit()

        Dim unused2 = MessageBox.Show("The spelling check is complete.", "Spell Checker", MessageBoxButtons.OK, MessageBoxIcon.Information)

        Dim simpleSound As New SoundPlayer("C:\Users\Tim\Desktop\Backup\Polly_Speaks4U_2_1_1\Resources\docsave2.wav")
        simpleSound.Play()

        ' Microsoft Word must be installed. 
    Catch COMExcep As COMException
        Dim unused1 = MessageBox.Show("Microsoft Word must be installed for Spell/Grammar Check to run.", "Spell Checker")

    Catch Excep As Exception
        Dim unused = MessageBox.Show("An error has occurred.", "Spell Checker")
    End Try
End Sub