File extension issues-indd and idml
I have a design in indesign 2018 cc and saved in the default format(indd). When i tried to open in indesign cc 2017, it is not opening. then i have saved in the compatible format(idml) and now it is opening... but when i try to save.. everytime... it is considering the file as a new document.. and when i overwrite it is saving...but now i am not able to open it... please help...

