http://www.robvanderwoude.com/escapechars.html
All DOS versions interpret certain characters before executing a command.
Some well know examples are the percent sign ( % ), and the redirection symbols ( < | > ).

Windows 95/98 and NT, and OS/2 too, also interpret double quotes ( " ) and ampersands ( & ), as shown in the Conditional Execution page.

In batch files, the percent sign may be "escaped" by using a double percent sign ( %% ).
That way, a single percent sign will be used within the command line.

In Windows 95/98 and NT, and OS/2 too, redirection symbols may be escaped by placing them between double quotes ( ">" ).
However, the quotes themselves will be passed to the command too, unlike the double percent sign.

Windows NT and OS/2 also allow the use of carets ( ^ ) to escape special characters. Even linefeeds can be escaped this way, as is shown in the Useless Tips page.

If you intend to "nest" commands with escaped characters, you may need to escape the escape character itself too.
In general, that won't make it any easier to read or debug your batch files, however.
Ich hätte jetzt gedacht, dass (ja/nein) als ein Klammernpaar gilt. Vielleicht geht es ja auch, wenn du die ganze Frage
SET /P exit=Wollen Sie das Patch-Programm beenden? (j/n):
Also sowas dann
SET /P exit="Wollen Sie das Patch-Programm beenden? (j/n):"
Vielleicht auch mal einfache Anführungszeichen ' verwenden?

Und wenn alles nichts hilft: Nimm halt was anderes statt den runden klammern. Zum Beispiel eckige [ ].