Internal libraries are the libraries coming with B4A, they are saved in (C:\Program Files (x86)\Anywhere Software\Basic4android\Libraries).
Additional libraries should be saved in another folder.
Click on Configure Paths in the Tools menu:
Enter the folder name for the additional libraries, it's up to you to manage this.
Copy all additional libraries into this folder.
You must NOT copy additional libraries into the internal libraries folder.
To use a library you must also check the library in the Library Manager Tab!