Myself Lakshman from India, I been face the problem was, i didn't able to change and move my storage settings like apps, videos, musics & pictures from internal storage to SD card.
Meanwhile the phone sometimes running dead slow, mainly if i open the recent calls it won't list out. This was happened several times. After that i was restart the device then it will recover.
So these two problems are the main defects while using my Nokia 6. Kindly send me the solution for the above issues as soon as possible.
If you need any details & discussions about my device please contact me via mail. firstname.lastname@example.org
Expecting yours positive reply
On inserting a SD card to the phone, You can initially select it to act as an External storage OR Extend the Internal Storage. You can manually move the data to SD using a file manager if you choose External Storage.
Ex - Solid explorer , ES file explorer.
Check the Google Files GO application which can be useful to clear out cache data and duplicate files.
Nokia 5 user here.