How are you saving the file (i.e., in what format)? Is the "As a Copy" checkbox checked? If so, it will not consider the document name changed.
If your file type is defaulting to PSD, that says you've done something to your file - add layers, channels, use 16 bits/channel, or whatever - that can't be supported in a JPEG file, so Photoshop is encouraging you to save it in a format that's capable of carrying those features.
I suspect there's no problem here in PS CS6 (I certainly haven't detected one), but rather something you've done to your file is what's making work the way you're seeing it.
FYI, I just tested this in PS CS5. I opened a single-layer PSD file, added a fill layer with a mask, and did a File - Save As. As expected, it came up with the .PSD type by default, and when I saved it specifically as a .JPG it did NOT change the document name.
> How are you saving the file (i.e., in what format)?
I opened a JPG file, made minor changes (crop, levels) and clicked "File|Save As...". The dialog box came up with PSD, not JPG. I had to change it to JPG to save.
> Is the "As a Copy" checkbox checked? If so, it will not consider the document name changed.
No. "As a copy" is not checked.
> If your file type is defaulting to PSD, that says you've done something to your file - ...
Yes, I am used to that behavior in earlier versions of Photoshop, which I have been using since version 4.
> I suspect there's no problem here in PS CS6 (I certainly haven't detected one), but rather something
> you've done to your file is what's making work the way you're seeing it.
I did not add anything to the file. The only changes I made were cropping and levels. No adjustment layers were created, no channels changed, no change to bit level - I know how to do those things, have done so in the past in earlier versions, and am familiar with the behavior of PS when you do so. This is not that.
> FYI, I just tested this in PS CS5.
Version CS5 works fine. When I open the same images in CS5, make the same changes, and click "save as..." it acts exactly as I expect it to - it defaults to JPG and the file name on the tab changes.
This is a version CS6 issue, not something I'm doing, that I know of. I am not ruling out that there might be something I'm doing or in the setup which is causing the behavior, but given I am only doing very simple editing on these images and I have not changed the default CS6 Beta setup, I have no clue what that might be.
It is erratic, as I said in the header - sometimes the program reacts the way I expect, more often it does not and I get this problem.
The only changes I made were cropping and levels.
Aha! Now I think I know what's happening.
You're using the new Crop Tool, and there's a bit of new functionality that's biting you I think: The [ ] Delete Cropped Pixels option.
If it's NOT checked, which is now possible on a Background layer, the Crop Tool will turn your image into a layer, so as to maintain the pixels outside the current edges of the document.
Try opening a JPEG, cropping with that setting in either position, and notice the name of the layer in your Layers panel in both cases.
BINGO! That was it. If I check "delete cropped pixels", or if I "flatten image" before saving, the "save as" dialog performs just as expected. That also explains why the problem was erratic - if I had flattened the image for some other reason, or hadn't cropped, the "save as" would work. I didn't make that connection until you pointed it out.
I should have thought about that - if it's possible to redo the cropping, the rest of the image has to be somewhere. I was thrown off by the fact that there was only one layer appearing in the layers list.
I'm glad the main problem was solved but, like you, I keep looking for a preference or option to check so that PSD does not show up as the default file type when saving layers. This happens even if I open a layered tif, do something to it, and want to resave it. PS wants to save it as PSD and I don't. I would understand if it was a PSD file to begin with, but it will do it for any layered file whether as "save" or "save as."