If you are trying to control the displays on your sign independently, but all the displays on your sign are reacting to button presses on the remote at the same time, the fix is easy.

This doesn't happen often, but sometimes if the sign gets a big static shock, it can reset the flash which stores the unique address for each of the displays.  To get the displays to operate independently they need to be configured with a unique address. 

Because the remote is controlling all the displays at one time, in order to set the address for each display, you'll need access to the switches on the back of each of the individual displays.  If you are dealing with an indoor sign on standoffs you can just reach behind it to access the buttons.  For a sign in an outdoor enclosure, you'll need to open up the enclosure to gain access to the displays.  Get the help of a licensed electrician as outdoor enclosures have AC line voltage inside.

To enter programming mode, hold the middle (RESET) button down for 5 seconds and then release.  Then use quick presses to the middle button to cycle through the options until you see A to the left of the display.  From there you can use up/down to adjust, when the number you want is displayed another quick press to the middle button will lock it in. 

Repeat this process for each display.  Start with an address of 1 in the upper left corner and increment the address by 1 as you work right and down.  When finished you should be able to use the IR remote to manipulate each display using Next Device and Previous Device buttons to navigate between displays.