There are two types of variant in VF04.

One is the selection variant before clicking the Display Billing List Button.

You can set the start variant via SE93 using the Change mode.
 

The second variant is the Billing Layout display variant. 

This is after clicking the Display Billing List Button.

After creating your layout display variant, you can set it by clicking :-

Settings ->
           Display Variant
                             ->  Administration

Select the layout display variant you want and click :-

Edit ->
        Define default settings
 

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