How I decode VBA with Change sheet name from cell A2

Dear
Kindly revise my code not work after change sheet name from cell name
Step
1.If change name Worksheet("INPUT") in Colum A2 suach as "U21-U21"
2.Change name at Work sheet("1") = same name in worksheet("INPUT") in Colum A2 suach as "U21-U21"
Remake
Name in Worksheet("INPUT") at colum "A2" can change name any time depends on what I wrote

Thank you

Private Sub CommandButton1_Click()
Dim my As Range ' Variable declaration at cell traget
With Worksheets("INPUT")
    Set my = .Parent.Worksheets(.Range("a2").Value).Worksheets(1).Name = "A2"
    
End Sub

Copy and paste this macro into the worksheet code module. Do the following: right click the tab name for your INPUT sheet and click 'View Code'. Paste the macro into the empty code window that opens up. Close the code window to return to your sheet. Change the value in A2 and press the RETURN key. You do not need to click the button.

Private Sub Worksheet_Change(ByVal Target As Range)
    If Intersect(Target, Range("A2")) Is Nothing Then Exit Sub
    Sheets("Sheet1").Name = Target
End Sub

You are very welcome.

I want to write down a short word at Colum "A2" (not selected word)

I'm not sure what you mean by the above quote. Are you saying that you want to enter a word at the bottom of column A? For example, in the file you posted, you would enter a word in cell A3. Is this correct? if not, please explain what you want to do in detail referring to specific cells, rows and columns.

I'm sorry but I still don't follow. I will explain how the macro I suggested works.
When you enter a name in A2 and press the RETURN key, the name of Sheet1 will be changed to the name that was entered in A2. If you enter a name in any other cell, nothing will happen, in other words, the name of Sheet1 will not change. Is this what you want to do?

"A2" refers to a cell not a column, so it would be cell A2 or column A. Maybe this is why I don't quite understand what you want to do. The macro does exactly what you described in steps 1 and 2 as long as you meant cell A2. I don't understand steps 3 and 4. Can you explain in the same way that I explained in Post #8. Please explain step-by-step.

My pleasure.

Now I can to revise as below
Sheets("Sheet1").Name = Worksheets("INPUT").Cells(2, 2).Value
I'm so sorry for not being explained clearly. It's my fault.
Thank you for your kindly support mate

This macro assumes that you still want to rename Sheet1 when you enter a name in cell A2. If you want to rename Sheet1 when you enter a name in a different cell, then change the A2 (in red) to the desired cell.

Private Sub Worksheet_Change(ByVal Target As Range)
    If Intersect(Target, Range("A2")) Is Nothing Then Exit Sub
    Sheets("Sheet1").Name = Worksheets("INPUT").Cells(2, 2).Value
End Sub