The CA-7 text editor is ... guess what ... a text editor for jobs that are in the CA-7 queue! Was that so hard to guess?
The CA-7 text editor is NOT anything like the TSO ISPF editor and there's very little overlap between the two editors as far as command syntax and so forth. SR (Save / Replace) replaces the original queue JCL with the changed JCL in the editor. Once this is done, using the CA-7 function to restart the job will use the modified JCL not the original JCL. And note that the queue JCL is changed, not the JCL stored in the JCL library, so the next time the job enters CA-7 it will have the old, unedited JCL not the changed JCL.