Cell "Notes"

Here are several potential solutions and workarounds you can try to prevent Excel from resizing your Note boxes.

Manually Resize and Lock the Note Box

Edit the Note: Right-click the cell → Select Edit Note.

Resize the Note box: Drag the edges to your desired size.

Keep the Note box open and save the workbook before clicking elsewhere.

Convert Notes to Comments (New Format)

If you don’t mind switching formats.

    Right-click the cell → Select Convert to Threaded Comment.

    Threaded comments do not resize randomly like Notes.

Additional:

Avoid using multiple monitors:

Excel sometimes glitches with comment box sizes on multi-monitor setups, especially with different DPI scaling.

Disable Auto-adjust for Comments:

    Go to File → Options → Advanced.

    Scroll to Display section and check Disable Auto-adjustments (if available).

Use VBA if your version of Excel allows it:

Sub FixNotesSize()
    Dim ws As Worksheet
    Dim cmt As Comment
    For Each ws In ActiveWorkbook.Worksheets
        For Each cmt In ws.Comments
            With cmt.Shape
                .Width = 150 ' Adjust width as needed
                .Height = 100 ' Adjust height as needed
            End With
        Next cmt
    Next ws
End Sub

Hope this helps