I've applied one of the 30 frame Poser 5 in the library walks to a character, and it's working. However, I don't like the closeness of the arms, so I tried to move them out a bit, but it only affected that particular frame. The ones before it were unaffected. I thought if you moved a part in a frame, Poser would tween the frames in between, figuring out where the arm would be.

The Walk Designer sets every single frame separately. If you look at the keygraph, you'll see that each frame has a key-mark on it. This is different from the usual situation you were expecting, in which you set a couple of frames and let the interpolation fill in between. So, if you want to move the arms in a more loose way, you'll either have to (1) alter each frame separately, or (2) draw a rectangle around the relevant arm joints, across the frames you want to change, and hit the minus sign at lower right to open up the keyframes for this joint. Then you can move them with the usual interpolation. This will, of course, get rid of the motions that Walk Designer gave to these joints.

Wow, that works! Thanks. It's amazing, every time I overcome one problem with this little project, another one crops up. Before this it was the cloth room. Hope this is the last one (he said just before the iceberg struck). :)

Don't think of it as "overcoming problems"... think of it as "discovering new universes". (I'm not quite kidding. When things are going perfectly smoothly, that means you're not learning anything.)

Ockham, How right you are!

In the graph editor it's possible to edit multiple keyframes. Highlight, then press control, the horizontal arrows will change to vertical...