I’m trying to install an SD card on a Galaxy J3 so as to be able to move apps from internal storage. These can’t be moved by going into App manager. I know there are supposedly two options to get round this:
1. Developer options, then set all apps to be movable to SD card. There is no option to move these in Developers options
2. Format the card as Internal storage - no option for this.
Are these options not available? Why would they say the phone can take a 128 Gb card if you can’t free space in internal storage?
The ability to move apps depnds upon how they are compiled, it's nothing to do with the device. The phone can take an SD card of 128GB for media storage, this was always the reason for the existence of SD cards.