Is there any way to batch change resolution, but not pixel dimensions?

Question

I was changing the resolution of my digital photos from 180 to 300 ppi individually as I edited them, but sometimes I would forget. Since I need the higher resolution for printing, I decided to automate that step by using PSE's "Process Multiple Files" feature. I noted that the Resolution selection was grayed out until I checkmarked "Resize Images." Since I didn't want to change the number of pixels, I left those fields blank.
When I started the automated processing I noticed it was terribly slow, so I cancelled it and looked at the resulting files. They had more than doubled in file size because PSE was nearly doubling the Pixel Dimensions! I don't want to try a work-around by "resizing" to the current pixel dimensions, because the processing still takes about 45 seconds per file, and if I've cropped the photos, the pixel dimensions vary. Is there an automated way to change only the resolution in PSE . . . quickly?
Also, I really wanted to double the resolution from 180 ppi to 360 ppi, but PSE limits my choices to either 600 or 300 or less. I've read about Scripts, but I don't think PSE supports them. I have version 6.
Thanks for some help.

Answer 1

Thanks for your input, and you may be right, but I'm not sure. I'm still trying to figure this out. I know it's the same photo on my monitor, but I keep reading that print resolution (ppi) is different from pixel resolution (i.e. 2000x3000.) This is my situation-- I'm sending the photos to a publisher for printing in a book. The publisher did not specify a size in inches--in fact I think the photos will be different sizes when printed on the page. They told me to send the photos in at 1600x1200 pixels. I've heard that 300 ppi is the standard resolution for publishing, so to get decent quality printing of my photos I thought I should increase the resolution from 180 to 300. But thinking about the different sizes, it seems that the resolution (ppi) will change depending on the size the photo is actually printed. At 300 ppi, a 1600x1200 photo will be printed at size 5.333" X 4". If a photo is printed full bleed on the cover of the book that is 8" x 10.667", then it will be 150 ppi. So, I guess you are right that I don't need to worry about the ppi resolution for the book photos.
Now, let me figure about what I need to print my own 4x6 photos. My digital camera was set to 16x9 jpg, so my workflow is to make PNG copies to work with and after editing, save them in the 16x9 format before cropping at 1600x1200 pixels, then sharpening before doing Save As jpg in Book folder. I was thinking I needed to change the resolution to 300 ppi when saving in the 16x9 format so if I want to later make 4x6 prints, I'll have good quality prints. But you have made me think a little harder--what I do is choose the 4x6 crop tool which takes care of whatever ppi resolution is needed for that size print. Oh good, you have saved me extra work. Thanks!
(BTW, I choose the 16x9 format because I was planning to use the photos in a widescreen slideshow, but my husband wanted something he could hold in his hand--hence, the book . . . and a lot of cropping!)