What you want to do: Arrange photos in a folder into an order that tells a story and keep them in that sequence.
The Problem: When you drag photos around in a folder to tell a story, they don't remain in the order you dragged them into:
If you add photos to the folder they will be added to the end.
If the folder is re-scanned or re-sorted, the photo order can become jumbled.
The Solution: Rename the photos in such a way that they remain in the desired order.
By drag-and-drop or sorting, get the photos in the folder into the order you want them to be.
Click on the first photo then type Ctrl+A (hold Ctrl key and push the A key) to select all photos in the folder.
Press the F2 key to open the Rename dialog box.
In the Rename Files box, type a description file name followed by -001
Example: "2020-08-15 At the Zoo-001" or "2021_05_01_campsite-001"
Make sure the file name does not contain any dots (.)
Numbering doesn't have to start at one (-001), it can start at any number, for example -121 when the last one is -120, or -1001 to make all suffixes 4 digits if there are more than 999
The complete renamed name including the - (dash) cannot be exactly the same as any photo in the folder.
When you added photos you can rename in two steps: first with a name which is (slightly) different, for example --001 instead of -001, then again with -001 - or - rename everything in the folder as "test-001" then rename again with a descriptive file name followed by -001
In the "Rename Files" box, ensure that the Date and Image Resolution boxes are not checked.
Click the Rename button and the files will be renamed in the order they appeared in the folder.
If the folder ever gets out of order again you can right-click on the Folder name and click Sort Folder By > Name to correct the order.
What you want to do: Collect photos from multiple folders into an album, and then drag them around into an order that tells a story.
The Problem: When you drag photos around in an Album to tell a story, they don't stay in the order you dragged them into. At some undetermined time in the future when you come back to the Album, the photo order will be jumbled.
The Solution: export photos using the Export function (see below)
It is possible to rename photos directly in an Album, but there are a number of problems with this including:
The actual photos in their source folders will be renamed, messing up the folder's photo names.
If a photo is in more than one album, that photos name will be re-changed each time another Album is renamed.
If an Album has photos from more than one folder (which is the reason for albums) the renumbering starts over for each folder.
These directions use the Export button in Picasa to make a copy of the photos and to rename them into alphanumeric order - all in one step.
Advantages:
The original photos remain unchanged in their original folders.
All edits are incorporated into the photos.
Multiple albums can incorporate the same photos.
Photos retain their previous name with a number prefix for sorting.
If the photos get out of order, a sort by Name returns them to order
Disadvantages:
The Photo "Albums" made here are really folders and the Photos take up disk space just like the originals.
Every time you change the "Album" (folder) by adding Photos or re-arranging them you have to rebuild the "Album" (folder).
Export Method of Maintaining Photo order
Put all the photos you want to show in a "blue" Album.
Arrange them in the proper order by dragging them to the order you want them to end up in.
Select the album name in the Album collection (go to another name and back if necessary so the album name shows in the tray in lower left).
click the "export" button in bottom middle of Picasa.
In the export box name a new folder name, select "Use Original Size", and select "Add numbers to files to preserve order"
Click the export button to export the pictures to the named folder.
Go to the Exports collection at the bottom of the folders list to find your new folder.
Right click on the folder name you just made and click "sort folder by" - Name.
The Exported folder now has the photos from the album in order and can be used any way you would use the album..
If photos later get out of order (either because they were dragged or sorted), simply right-click on the folder name and select Sort Folder By > Name.
If you want to re-arrange the photo order in the future there are two choices:
Delete this folder and rebuild it using the Export Method of Maintaining Photo Order directions above.
Re-arrange and/or add photos to this folder, then use the Order of photos in Folders topic above to rename them in order.
If you must have an Album, click any photo in the new folder and type Ctrl + A (hold Ctrl key and type A) to select all photos in the folder, then right-click on any of the photos and select "Add to Album > New Album. Type a new name which will be your new album. You may need to sort it by name.
More information:
How to organize, move, copy and rename photos: https://sites.google.com/site/picasaresources/picasa/how-to-reorganize-your-photo-collection