you have to format the card as internal.

 

Settings > About phone > Storage > scroll down to > Storage settings > Tap on opens where you want to store Camera, Themes and Gallery.
Works OK for me.

 

that only moves part of the app to the card......mainly data will be stored there. the rest of the app will still reside on the phone. this only frees up a small amount of space on the phone. to truly us the sd card as the primary storage, you will need to do what i suggest earlier.....and that is to format the card as internal.

but doing so has its disadvantages as well. for one, the sd card can't be used as a normal sd card. you can remove it or use it a portable storage device. it is now encrypted as part of your phone's internal storage system. also your card will have more wear and tear by doing this as the phone will be running everything off of the card. so it will read and write more often. this will increase the risk of the card failing and thus you will lose all of your data along with the card.

so your suggestion is a good one, i just wanted the op or anyone else who reads this thread know what they are getting into if they format the card as internal.

 

I agree with your advice but the thread starter wanted to move Apps to an SD card and upon re-reading the Post I seem to remember that back in the days of my Huawei Ideos, I used Astro File Manager from Playstore which enabled Apps to be moved to the external SD card.
Not ALL Apps could be moved but the idea was for cell phones with small internal storage capacity.
My Redmi 7 has 31.3GB's of the total 64GB internal storage in use.
There is an excellent article in the How to Geeks regarding how much internal storage is really required in a cell phone (relates to iPhones but it is a good guide)..

 

apps to sd card moves only portions of the app....not the entire app. it moves certain things of an app like data to be stored on the sd card. and you do not need a file manager to do this.