SD card using for internal storage

[femc114]

When I try to use the sd card as a internal storage, I cannot find a way in asus 6z phone and I read a comment from here mentioned by Anders_ASUS. 
He said the policy is changed by google and it is not possible to use sd card as an internal storage in android pie os. However I see some YouTube contents which show it is still possible to use sd card as a internal storage even in the android pie os. It shows  that this restriction of using sd card as an internal storage is decided by manufacturer not by google.
I don't know which is correct information but based on the above content, I doubt that asus intentionally restrict this by any reason and also know the way to fix it.
Many people think that they can use sd card as an internal storage(save and install app in sd card) when they choose the asus 6z phone.
I hope asus can find a good solution with this.

[Anders_ASUS]

You can use it as storage for media files but you can't run apps from your SD card. Google made this change because running apps from a SD card can cause all kinds of issues. The built in storage in most phones have increased more than the size of apps so there is not as much need to store the apps on a SD card anymore.

[jimo1921]

I've try to use external SD card to keep tidal library.
And I can't. Why?

After 1 min. Download or after screen lock ZenFone freezes. And only long reset can help.
On internal memory works fine.
Two cards 32 and 64 GB Kingston class 10.
What is more, see on screens.








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