Fix color of a series in Chart

I am trying to fix color of data series in Line chart, but couldn't find an option.

Here is the requirement
1. I have product profile margin (%) by region
2. Each region has it's own profit margin goal
3. I show one region (goal and profit margin %) at a time using line chart

Here is an example:

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Region: NE
Product: Prod1
Margin: March - 2%; April - 9%; June - 11%

Region: NE
Product: Prod2
Margin: March - 5%; April - 9%; June - 5%

Region: NE
Product: Prod3
Margin: March - 5%; April - 8%; June - 9%

Region: NE
Product: Goal
Margin: March - 4%; April - 10%; June - 8%

----------------------------------------------------------------------

Region: SW
Product: Prod1
Margin: March - 5%; April - 9%; June - 11%

Region: SW
Product: Prod4
Margin: March - 2%; April - 11%; June - 15%

Region: SW
Product: Goal
Margin: March - 6%; April - 8%; June - 12%

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I filter the region (select one at a time) on pivot chart and it shows the line chart correctly. The issue is that excel changes the "Goal" line color each time. I want to fix it so it always use the same color for "Goal" line when I select the region. Is it possible?

Thanks,
WC