MENA Indesign is defaulting to right-to-left. Pdfs are arranged right to left if i organize pages

If you add another language as it is with MENA versions the case, the last installed version will be the default language.

But often the additional language and their settings are only needed for not so many documents. What you need on a daily basis is your own language.

There are many settings and it is easy to oversee and to forget them. You will want to set up the program that everything is in its settings on the correct place and if you work in a team, in the same way as your colleagues are working and used to it. 

Bevore you install othe languages, save a simple default document in that language. 

Do get everything stick for any new document you have to cange the proberties when no document is open. 
Therefore is the easiest and fastest way to take that default  document where all settings are correct as you need them.

When no document is open, import all language relevant styles — paragraph,  object, table and cell styles —and let them override the new defaults. 
Now you go — without any document open—to document setup and change binding, size and units and close that dialogue. 
Quit InDesign to sae all changes in case of an unexpected crash.  

When you create a new document you get all settings what you have dine, when no document was open. 

You can go one step further to create for each setting (e. g. language, client, purpose, …) an INDT template file to avoid repeating steps you will always do in the same ir similar way.