If your MiFi is appearing for some devices but not others then chances are that the MiFi is broadcasting in a mode which is not compatible with those devices. You can make a quick config change and see if it helps.
To change the 802.11 Mode:
1. Power on the MiFi
2. Navigate to http://mifi.admin
3. Sign into the MiFi in the upper right hand corner
4. Click on the WiFi tab
5. Switch the 802.11 Mode from G+B+N to G+B
6. Click Apply
7. Test your connection on the other devices
Please note that you will need to find a computer which can connect to the MiFi before you can complete these instructions. If you do not have one available then ask a friend and borrow thiers for a few minutes. Otherwise you could stop by the Verizon store so they can perform the steps for you.