How to Format Micro SD card to Use in Phone

I've done it before but can't remember how I did it. I have two LG 500G cell phones. They use a 4 GB micro SD card to store info (in addition to a sim card). I want to save all my contacts to one SD card and transfer them to my computer and then copy them to the other SD card so both phones will have all my contacts. I was hoping to save time by not having to enter them all on the 2nd phone. And I was hoping to keep them on the computer in case either phone gets lost or damaged.

So the one SD card is formatted and the phone recognizes it. I did that months ago and thought I knew how I did it. But I have 3 new SD cards (bought from different sources). I've formatted them on the computer with FAT32. However, my other phone doesn't recognize them. And I can't format them on my phone. When I try to switch the memory on the phone from handset or sim to memory card, "memory card" is grayed out so I can't select it.

What am I doing wrong? I think I'm doing everything I did the first time, but I really had no idea what I was doing then. I'm one of those people who just keeps pushing buttons until something happens, and sometimes I get lucky. LOL I can't seem to get lucky today though. Can anyone help me?

NancyAnn