Change Slicer Values Color (Border)

It seems that that border was added through a custom theme/JSON. Try going into the Slicer settings and select Reset to default in each of the Visual categories

Hi,ray_aramburo ,thanks for your concern about this issue.

Your answer is excellent!
And I would like to share some additional solutions below.
Hello,gadiel .I am glad to help you.
If you want to modify the border format of a single visual, you can set it via borders in Visual/General
General>Effects>Visual border

You could change the visual border color/Rounded corners/Width
 

You can also modify the entire reporting application's Theme.
URL:
Solved: Clear Selections Button on One Slicer - Microsoft Fabric Community

Power BI Desktop: View>Customize current theme>Name and Colors>Advanced

Please try to modify a series of parameters in Advanced in Customize Theme, which controls a series of parameters of the whole report application theme.

Note that the color of the slicer dropdown box seems to be gray by default and cannot be modified, but you can modify the font and the outer border and a number of other display effects.
I tested it and found that no matter which theme I choose, the color of the inner border of the dropdown box remains the same.
Like this:

You can try writing a theme script file to artificially modify the theme style you want.

URL:
Use report themes in Power BI Desktop - Power BI | Microsoft Learn
 

I hope my suggestions give you good ideas, if you have any more questions, please clarify in a follow-up reply.

Best Regards,

Carson Jian,

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