I have a galaxy grand prime I have been trying to install a sd card but it's not reading it I have installed 3 different ones and when I go to storage and under sd card it says mount sd card but it's not high lighting it so that I can install can someone please help
Power off the phone, insert the microSD card, then power the phone back on. The phone should detect the card and may ask if you want to format the card. Once formatted, the 'mount SD card' option should highlight. To get to the menu, go to: Settings > Storage > SD card - mount.
Rikkster's right! In fact, some Micro SD Cards work better than other. I've experienced that myself with my previous phone. I had difficulties with a specific card that was improperly ejected randomly. I decided to try a high-end model and didn't have any issues after that.
Rikkster also mentioned the card capacity and that's a very good point. You can add up to 64 GB (microSD) on the Samsung Galaxy Grand Prime. However, if the storage capacity of your microSD is more than 64GB, your phone might not recognize it.