Crystal Report Fields Ungrouping

I am working with existing crystal report and at the moment I am totally helpless to un-group two fields added in Text object.

  Basically I want to add formula to one of the embedded field and I can not select that, below is the image

Here you can see two fields are embedded in a Text control, I wanted to select the Top (Extra_Merch_Desc...) field, Kindly help in this regards.

I have done this so far.

1. Select the required field(s)
2. From the Format menu select the Format Field option
3. Click on the Font Tab
4. Press the [x+2] button to the right of the Size drop down
5. Enter the following formula: 

   IF Len({Customer.Customer Name})>15 Then 8 else

   IF Len({Customer.Customer Name}) in 10 to 15 Then 9 else 10

6. Press the Save and Close button

Reference Link

I have double clicked the Text box and found two options :

• Text Formatting...
• Format Embedded Field...

When I do modify the Formula and "Save & Close Option Press" , it saves and I can see Formula in the Formula box, but after exiting from Formatting Box next time that formula disappears.

Below is the formula for the font change:

if Length({myfield}) < 50
  then 16
else if ((Length({myfield}) >= 50) AND (Length({myfield}) < 80 ))
  then 13
else if ((Length({myfield}) >= 80) AND (Length({myfield}) < 100 ))
  then 11
else
  10