letter A problem

Dear Heba, I use the Middle Eastern version of Adobe InDesign for many years and I often switch back and forth between English and Arabic languages in my work. Tell us more about the issue of the preference so I can help you, just explain what you do exactly so I would know what to suggest.

Does the letter A work on your keyboard in other applications? It is not uncommon for keyboards to fail. If the problem is just in InDesign this is often a sign of a software conflict. It's also possible you have inadvertently assigned it as a keyboard shortcut to change the language assignement if the shift to Arabic seems related to typing the A.

Language is assigned as a character attribute to your text so that you can have approriate language assigned to individual words. The language settings in the preferences do not assign language to the text, they set the choice of dictionary that will be used for each language to do hyphenation and spell checking when more than one vendor's dictionary is available.

In general, you assign the language for the bulk of your text as a part of your paragraph styles, then change the language for required special cases of foreign words by selecting them and changing the language with a character style or local format override.