why do new mask layers always go above the selected layer?

[SG Pilgrim]

I thought I saw a setting a some time in the past where creating a mask layer always attached it to the selected layer instead of above it. In fact, that used to be the default behavior, correct? 

How can I re-enable the behavior that if a layer is selected, and I click the mask icon, it always attaches to the layer, not above it?

 

[Obscured]

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[SG Pilgrim]

Thank you!

I had the assistant disabled, so didn't see the option.