You're asking a question with prior discussions so I'll keep it short.
To date Android has yet to offer a method to install apps to external memory directly.
Not only that but in newer versions the move to SD Card was removed.
There are folk that can't accept the thousands of prior posts on this question and get really upset. Not much you can do for them.
If you are unlikely to have such a phone then you know to keep it as clean as you can and learn that next time you want more internal storage.
Hi all, myself Alon Solomon, I have a micromax android phone having almost all the features. I have the 4 gb of internal storage, and it is almost filled but, but I also have the 16 gb of external storage, where about 5 gb of storage space is left and default memory location is also to the external storage, but whenever I am downloading a new app from google play store, there are insufficient memory space showing. What to do to install the required apps into my phone?