For auto saving the new files with an increasing number you must FIRST create my universal CountUp
macro. The source code with description can be found at counter
or compiled in the macro files in the zip archive you can download at Macro examples and reference for beginners and experts
THEN create the following macro. You have to adapt the red highlighted filename with path. If you think you will not produce more than 999 files, you can modify all 0000
or less (00
should be also enough for you).
Make sure you have only your source file open or it is the most right one in the file tab order because of possible problems with setting Move to nearest left tab after current tab is closed
The following macro is a simple version of the macro posted at Splitting Big Files
Key UP ARROW
PlayMacro 1 "CountUp"