How to set preference to automatically save file as PSD in same folder as original file?

I found that if go to "Export" under "File", then "Export Preferences" and change the check box under"Export Location" to "Export the assets to the location of the current document" a "Save As" will bring up the original location.

I also have this issue and it is most frustrating.  And no, it is ridiculous to have to write a script to have photoshop act as it formerly did.  And like others I do not see any solution in the replies.  Why has photoshop themselves not replied with any information as to this basic change in performance?  There are many other subtle changes to photoshop's performance with the latest updates for which I have not seen any documentation.  Most disappointing.

I too am having the same issue.  Nothing written so far addresses this issue.  Each time the answer is to use the File Handling Preference is Photoshop.  Even if you do select the "Save As to Original Folder" Photoshop will not do this.  I am running Windows 10 and the lastest version of Photoshop. 

The issue again.  Using "Save As" to save a file back to it's original folder without having to direct it to do so each time you use Save As isn't working. 

I don't use Lr – just make sure that you save/close or close/save rather than save as and you should be good.

Try googling the topic of a roundtrip from Lr to Ps back to Lr.

Does any know what the save as option of 'image previews' means in file saving options in the preferences box?  Why 'previews' rather than just 'image'?  

From Lightroom I used to be able to open any image file in  Photoshop, edit it, then close the image file which would bring up a 'save as' window where I simply specified whether I wanted to save as a Jpg, TIFF or PSD, etc.  But it would always save to same folder that the image that I just brought into Photoshop from Lightroom was in.  And then I would be taken back to Lightroom automatically where the edited image would open up.  And next to the unedited and any previous edited versions.  I forgot to add that now when I go back 8nto Lightroom it hasn't saved to my Lightroom catalogue and I have to import it.   So now I'm wondering if there is some preference in Photoshop where you ask it to add the saved image to Lightroom catalog too?

You could use a script.

The following code will save a PSD to the same location as the original, overwriting the original and automatically close the file without any dialog window. Use at your own risk, I have tested the script, however you should make sure that you are happy with how it performs by working on dupes before putting it to use on original files.

#target photoshop

/* Start Unsaved Document Error Check - Part A: Try */
unSaved();

function unSaved() {
    try {
        app.activeDocument.path;
        /* Finish Unsaved Document Error Check - Part A: Try */

        /* Main Code Start */

        // File Naming Code
        var d = app.activeDocument;
        var dName = d.name.replace(/\.[^\.]+$/, '');
        var dPath = d.path;

        // File Saving Code
        var saveFilePSD = new File(dPath + '/' + dName + '.psd');
        SavePSD(saveFilePSD);

        // PSD Options
        function SavePSD(saveFilePSD) {
            psdSaveOptions = new PhotoshopSaveOptions();
            psdSaveOptions.embedColorProfile = true;
            psdSaveOptions.alphaChannels = true;
            psdSaveOptions.layers = true;
            psdSaveOptions.annotations = true;
            psdSaveOptions.spotColors = true;
            activeDocument.saveAs(saveFilePSD, psdSaveOptions, true, Extension.LOWERCASE);
        }

        d.close(SaveOptions.DONOTSAVECHANGES);

        /* Main Code Finish */

        /* Start Unsaved Document Error Check - Part B: Catch */
    } catch (err) {
        alert('An image must be both open and previously saved before running this script!')
    }
}
/* Finish Unsaved Document Error Check - Part B : Catch */

https://prepression.blogspot.com/2017/11/downloading-and-installing-adobe-scripts.html

Once installed, you can set a custom keyboard shortcut to the script.

Yes, that was the first thing I checked but it doesn't make any difference.

If I can understand your problem correctly then you should see dialogue asking whether you want to save changes with three options. If you click Yes then Photoshop should save file next to one which is open from Lightroom without any dialogue. I tested with Save As to Original Folder unchecked and it does not make any difference. Photoshop is saving file as expected without any Save As dialogue.