mesh with armature: problem with editing the mesh

I’m stumbling over the following problem: I have a mesh and an armature. Since the deformation of the mesh by the armature was not so good, I tried to change the location of some vertices to get better results. The changes are only visible in Edit mode, when going to Object mode, the mesh returns to the original look. Vertex groups are already defined for all bones and vertices assigned. I unchecked the “use armature” button in the “Add modifier” section, but the problem persists. Why can’t I adjust the mesh any more?

Do you have shape keys defined? If so, check which shape key you have active when you go into edit mode. You may be editing the wrong shape key. To make edits apply to all shapes, press WKEY in edit mode and select “Propagate to all shapes” with the verts selected whose shape you want propagated.

That’s it! Thanks for your help.