How to make part of the text in a cell bold

I want "some" of the text in my cells to be bold. I'm tried both these codes bellow

Workbooks("AH responsible Macro Enabled").Worksheets("testSheet").Cells(i, 1).Characters(7, 5).Font.Bold = True

Workbooks("AH responsible Macro Enabled").Worksheets("testSheet").Cells(i, 1).Characters(7, 5).Font.FontStyle = "Bold"

Instead all my cells are coming in bold. why? The text inside the cells is: Hello There, How are you doing? I'm doing fine this is a test.

After I run the code i think it should read: Hello There, How are you doing? I'm doing fine this is a test.

Anyways, I'm wondering why the whole cell is coming in bold. I'm really confused.

Edit: Using Excal 2010 and VBA 7.0 for Excel

Thanks.

---------- Post added at 11:49 AM ---------- Previous post was at 11:42 AM ----------

I think I know why.

previously I use this code which I commented out:

Workbooks("AH responsible Macro Enabled").Worksheets("testSheet").Cells(i, 1).Font.Bold = True


I just went into excel sheet and removed the Bold setting.

Am glad you solved it on your own.

Select Thread Tools-> Mark thread as Solved. To undo, select Thread Tools-> Mark thread as Unsolved.

It works for me.
Does your last comment mean the request has bee solved? In which case would you mark it as solved so that others don't waste time.