Welcome to the wonderful world of Repeats and Endings.

The first thing to realize is that this is essentialliy a PRINT function. You can add bars from the dialogue, but most users will tell you to create the song in linear form first, and then add the repeat attributes. Since you are not going to use the BIAB repeat function, change the number of repeats to 1, and the number of bars to the total in your song. Pick a number, say 200, and go back and change it when you are finished. These boxes are next to the tempo and key above the notation area.

So take the four measures and copy them 3 more times to get a total of 16 bars. The using the repeat dialogue, make a repeat starting at bar 1, with 4 bars in the repeat, repeating 4 times.
If you want to change to 3 repeats, you must manually delete the last four bars, and the EDIT the repeat dialogue. Just right click on one of the bars, and select Repeats Codas etc. and then click the edit button on the bottom left. The repeat will be highlighted, so click EDIT, and your original repeat will show. Change the number of repeats to 3, and click Make Repeat.

If you want to add an additional repeat later in the song, the process is the same. Create the bars you need to repeat first, then right click on one of those bars, and select Repeats, Codas as before.

However, this time when the dialogue appears, select EDIT LIST. This will highlight your existing repeat, as before, but this time click APPEND to creat a new repeat. Don't forget to click MAKE REPEAT to close the dialogue.

You do this for all of the repeats, endings codas etc.

The key is that BIAB will play what ever you have created in the notation window, starting at bar 1 and continuing to the end. The fake sheet will show the results of the repeats, endings, coda dialogue. Your task is to make sure these are the same. For the most part this is a tedious but workable problem.

Good Luck

BIAB for Windows Version 2019 (643)
Windows 10 (1909)