I thought it was a simple matter to rename some of my tubes which had prefixes of pajk and pa. I've simply used my file manager utility, cursored to my tube folder, then right-clicked on a tube name which then allowed me to edit the filename. I was highlighting the old prefixes and then typing jk.
Some of my tubes were too large, so I decided to reduce the size. Of course each would have to be exported again. When I opened the first tube using the browse feature in PSP 7 [File/Browse] I discovered something I never knew before - even though I had changed the actual filename on my hard drive, PSP's tube information screen did NOT change. It retained the filename given to it when exported before. Since using the tube showed the new name, I wasn't aware of this.
This isn't such a big deal for me as pajk-anything.tub still identified the tube as "Pixel Art by Joyce Kohl. The pa was just a simpler way of identifying my tubes from others. Then when I created this site, I decided to change the prefix to jk and was simply renaming tube files not knowing that if I changed filenames, it might also be necessary to select to export them as tubes again so the information in PSP's tube export screen could also be changed.
But then I discovered that if I renamed tube thumbnails from within PSP's File/Browse, or even if I didn't rename a tube, when I opened a tube from the thumbnail image, then choose to export it again, the tube name slot is blank.
Now when I rename tubes, I use PSP's File/Browse, right-click on the filename, change it, open the tube by double-clicking on it, then export it again and type in the new filename.
UPDATE: It was brought to my attention that I neglected to mention an important fact. If you simply open a tube, then give it a new name and export it again, you'll have two identical tubes but with different names. Be sure you delete the old tube!