I have accidentally ordered item barcodes with a different configuration of letters and numbers. Can I get Amlib to recognise these barcodes?

Yes, it is possible to configure Amlib barcodes easily. You can adapt the combinations as required, while remembering that the leading and trailing characters can be a combination of alphanumeric characters by the use of symbols:
- # indicates any numeric character
- ? indicates any alpha character
- & indicates any alphanumeric character
Enter I in the first columns for Item Barcode setup and enter B in the first column for Borrower Barcodes
After setting up the relevant Barcode setup, use F6 Test after indicating if the Barcode is Item or Borrower by changing the radio buttons at the top
For example, set Amlib to read Item barcodes with 3 letters and then 4 numbers:

Go to Main > Supervisor > CheckDigits. There is a guide at the top right hand column of the window that states: The leading and trailing columns can be a combination of alphanumeric characters showing the symbols to use to create the customised barcode as shown above.
Press F1 New.
Type an I in the first column (this is the letter I for Item).
Tab over the next two columns to get to the column for Leading Chars (characters).
Enter ??? in that column (if you look in the guide at the top right hand section you can see that the ? stands for an alpha character).
Tab to the Trailing Chars (characters) column and enter #### (# stands for a numeric character).
Click F3 Save.
The length column will be populated.
You can then test out the barcode by changing the radio button at the top to Item and scanning the barcode. Click F6 Test.
If it displays Valid Check Digit, then it is set up correctly for the barcode.
Log out of Amlib completely and log back in before using the new barcodes within the modules.