You may be asking "Why can't I adjust the opacity of the Borders in the latest version of Exposure?". Well, the simple answer is that Borders should not have opacity. The large majority of the borders have no use for opacity, so it's not included. Exposure 4 had an opacity feature for borders, because it was a very limited tool and had one slider that controlled everything for every texture group.
Now that you can import your own textures, you can import these borders into the Texture section of Exposure Overlays and have full control over the opacity of the border. This zip file contains the original textures without any opacity, reproducing the same effect as Exposure 4.
You can download the Exposure textures from here
Here is an example of the border vs the texture. You will see that using the same border in the textures section allows you to replicate the look from Exposure 4.
1. Exposure 6 border only (border name Damaged 5)
2. Exposure 6 border used in the Textures section (Full textures from the Damaged 5 Border)
3. Exposure 4 example as compared image number 2. (Preset Wetplate (damaged surface))