Best parallax plugin, but not perfect

I’m having some minor issues on my website.

Parallax effect doesn’t work when the speed is 0, like it’s not enabled, instead of “fixed” as expected.

I set the size to cover, and when the speed is negative, the image zooms in unexpectedly.

No responsive function-I used “Conditional Blocks” to achieve this, but it makes the page dynamic and cannot be cached by the caching plugin.