changing axis

hello

  i have drawn something and I realized that blender has the z axis pointing up, is there a way to "not" do anything with the model and just make y axis now pointing up?

It’s not customizable in Blender, last I heard.
There’s a bunch of customizable options that are going to be possible with some of the planned recoding, and that’s one thing that some people have asked for. Check around on the developer’s area at Blender to see if that’s on the list to do. I’m not sure why it matters, unless you’re used to another program or maybe exporting to one.
[edit] Doh. Fligh’s answer below is of course, right again. I thought you meant how to change the program, not change the model. Sorry!

Add or select an existing object with a Y-Up axis, Shft-RMB select first the Z-Up and then the Y-Up (so the Y-Up one is Active. Ctrl-C >> Rotation.

There’s also an “Axis Orientation Copy” script under Objects.

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is there a difference between doing that vs just rotating the original object?

Yes, Ctrl-C >> Rotation changes only the rotation of the Axis, not the Object and its linked Data (Mesh, Armature etc). If this is related to your export to Y-Up question I don’t know the answer, I just don’t export enough to know.

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ok, i got it thank you