How to change speed dial entries on analog phones?

[Frank86]

I have analog phones connected to a Grandstream GXW4224 switch.
The analog phones have speed dial buttons, one of them dialing an old extension that I want to update to a new one.
How would I do that?

 

[Evolute IT]

Using the phone's manual my friend. There's no BLF on those phones. It's probably, dial and hold the button until it flash or something.