How to replace Smart Object in Photoshop mockup and make it fit?

Question

I have purchased a mockup and am trying to replace a Smart Object in it by selecting in Photoshop CS6 menu:

"Layer" -> "Smart Objects" -> "Replace Contents..." and then selecting my 2000 x 2000 pixels PNG file:

Replacing works, but the inserted PNG is too big and is cut off by a mask, while I need it to fit:

When I was looking at the mockup promotional image, it seemed to me, that this is the case (fitting in the replaced PNG and JPEG files):

But eventhough I have also used the same wooden background coming with the mockup package - it is fit there, but cut off in my image, why?

Answer 1

These mockups usually have smart objects that are sized and transformed correctly so that you can open the smart object (by double clicking the smart object in the layers panel) and place your artwork inside, rather than replacing the smart object with another that contains your artwork; which I assume is what's happening here... So try opening the original smart objects and placing your artwork inside instead of replacing the entire smart objects.

In any case you've just got a flat smart object masked to a rectangle so it's easy enough to fix the sizing on the smart object and just leave the mask intact instead...

Just unlink the mask and the smart object by clicking the link icon between the mask and smart object thumbnails in the layers panel, make sure you have the smart object selected (not the mask) and hit cmd+T to transform the smart object.