Most decoders don't use the F3-short whistle/horn default, only one or two manufacturers use it. On most sound decoders it's the coupler crash or some other sound.
DCC is used worldwide so what you call "default setting" is used mainly for North American prototypes.
Here in the UK, trains do not use a bell, so function F1 is used for something else.
In my experience, the higher Functions are not standardised and so I use an index card system. Each loco has an index card which lists Function Numbers and what a single press,double press or hold down actually does.
I can vouche for what Ed is saying about the Loksound V2.0 decoders. IIRC, for steam: F1 was the "double" whistle; F2, the bell; F3 the single whistle. It's possible that F2 & F3 are reversed. However, those should be the correct sounds for those three buttons, for that particular sound decoder.
While most steam sound decoders generally use F1 for bell and F2 for whistle, F3 (and F4) are not always associated with the whistle because the NMRA didn't standardize the function buttons so the manufacturers are at liberty to use them however they choose. F3 is sometimes a short whistle and other times a coupler clank. On the TCS WOWSteam, F2 is long whistle, F3 is short whistle, and F4 is pre-recorded quill whistle. For Loksound, F3 is coupler clank and F4 is blow down for the boiler.
If those sounds in that orientation are important to you then most sound decoders will allow you to remap the function buttons to your liking. While you can do it manually, it's usually easier to achieve using a programming track and JMRI Decoder Pro.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
I recall reading that the early versions of the Märklin Trix locomotives used a Loksound V2.1 decoder with different function assignments than the usual ones. I have a Trix Mikado but I installed my own Loksound Select in it.
I believe some LGB is using the Märklin digital system.
More here:
https://elmassian.com/index.php/dcc/specific-manufacturers/lgb-dcc-mts
Regards, Ed
A friend has an LGB loco and I was surprised to learn that by default the LGB decoder did not use the traditional standard of default mapping F1, F2 and F3 to the bell, airhorn, and short airhorn. This got me wondering. Are there any other popular sound decoders that do not map F1, F2 and F3 as a default setting?