Forgive a long-winded answer, but since you might be new. . .
There are three things: hardware (the scanner itself), the firmware (the brains of the scanner) and the memory of the scanner.
Hardware is pretty fixed and nothing to do to update it.
Firmware will be updated as bugs are discovered in new products. However these updates are rare as time goes along (all bugs get discovered) and then vanish as scanner manufacturers come out with new models.
Here is a link to the Uniden site where you can get the program to update your scanner's firmware along with the latest (though many years old) firmware. Your scanner may "work" fine without the firmware update, rather updating the firmware may mean the scanner working at its best.
The last thing is the programming software for the memory. That's the stuff you use to download data from RR and program this data to your scanner from your computer. Yes you can do it by hand on the scanner keypad, but its laborious beyond mention.
There are three software packages I'm familiar with that will do this task:
Butel ARC XT
ARC XT software for Uniden BCD996P2 BCD346XT BC346XTC BCD396XT BC346XT BCD996XT BCT15XT BCD325P2 BCD996 P25 models scanner free demo
Proscan software:
https://www.proscan.org/
Freescan:
FreeSCAN - Sixspot Software
Butel and Proscan cost $ so you might load the trial version first. Freescan is free.
Just like with any other software, each has its good and bad points and you'll have to decide which you like.