Stop Checkbox Sub From Jumping To Other Checkbox Subs

I have 3 checkboxes; when one is checked, a set/range of rows should be visible. Only 1 checkbox should be checked at a time.

If checkbox 18 is already checked, and checkbox 20 is then checked, I want the first checkbox unchecked and the rows for checkbox hidden.

I'm using the following code. It works great as long as I check and uncheck the same box before attempting to check another box. But if Checkbox18 is already checked with its rows showing, and I then check checkbox20, the checkbox20 sub runs and as I step through, it jumps to sub checkbox18.

How can I stop my subs from jumping from one to another?

Code:
Private Sub CheckBox18_Click()
If CheckBox18.Value = True Then
Worksheets("TRF").Rows("36:41").Hidden = False
Worksheets("TRF").Rows("42:64").Hidden = True
Worksheets("TRF").Rows("65:76").Hidden = True
CheckBox19.Value = False

[Code] .........