How to add blur / round corners to only white rectangle layers

Question

I want to add a blur or rounded rectangle to only the white rectangle layers, which are behind the text.

Trying rounded rectangle with the layer selected, only modifies the main layer.

I have tried using a Layer Mask (white), putting the mask to selection, and applying the filter to the mask, then apply the mask... Is Layer Mask = White the wrong option?

Applying the Layer Mask does not work; it just shows the original layer.

When I apply the rounded rectangle to the mask, it rounds the mask, but on apply, it doesn't change the actual Layer.

Is there any way that I can crop to Layer Mask?

Any tips for a frustrated noob? I've tried following these tutorials, without success: How to apply a filter to a layer and its mask at the same time (in a single pass)?

Answer 1

A simple solution:

• Select each rectangle in turn
• Make a rectangle selection on the rectangle, with rounded corners and/or feathering
• Select>Invert, Delete

Answer 2

With layer masks, white equals visible and black equals invisible for the content of the layer they are attached to. The description above doesn't mention using black color anywhere, so I assume this wasn't done.

A possible approach with a rounded rectangle would be to use a black layer mask initially, and then fill a rounded rectangle with white.

Seems overly complex for this case, but works as well if the result wouldn't be rounded white rectangles.