Which software is right?

[Oleum]

In version 1.58.1, the hardware versions 4 and 4.1 are not mentioned in the info. While they are mentioned in the version history.
Which one should I use for a 4.1?

 

[joepasquariello]

Both of those TeensyDuino versions support T4.0 and T4.1. In the drop-downs, you should also see 0.59.x, which are the beta versions of upcoming 1.59. Even though they appear to be older because of the leading 0, they are newer, and I would recommend using the latest one of those, which should be 0.59.4. Versions 1.58 (and 1.59) have updated tools (gcc, etc.), and are preferable to 1.57.x

 

[PaulStoffregen]

the hardware versions 4 and 4.1 are not mentioned in the info

Click "More info".

It is same info, but printed in a weird order (thanks Arduino IDE) and truncated. You'll see the rest of the supported boards when you click "More info".

 

[Oleum]

Yes, that's right, the button will take you to your website. There, quite far down in the history section, you will find the information about version 1.58:
Updated toolchain to gcc 11.3.1 for Teensy LC, 3.x, 4.x

Thank you