This article explains how to use GIMP’s Layers palette, starting with finding the nearly hidden Link Layers option. It includes information on how to link and unlink layers, and what transformations you can apply to linked layers.
Gimp How to link layers
You link two or more layers together so that you can apply transformations to each layer in the same way without having to merge them first. This gives you the flexibility to perform subsequent transformations independently. Although Link Layers lets you move, resize, rotate, and flip layers at the same time, it only applies to these types of transformations. You cannot apply a filter to multiple linked layers at once. You must apply the filter to each layer separately or merge the layers first.
Linking layers is simple once you know how, but because the buttons aren't initially highlighted, it's easy to miss them.
Open GIMP with your multi-layered project.
