Bass Synth in Musescore

Hi Musescore!
I love the new update that you made, but I've being had some difficulties using it.
In the previous version (Musescore 3), the program allows me to choose the instruments and then change the sound in the mixer.
For example, in acappella scores, I like to use the Synth Bass 1, since for me the sound helps me to transcribe acappela songs.
But with the new version, it doesn't allow me to change the sound to Synth Bass 1 in the MS Basic.
I read some questions in the forum that said that synthesizer sounds were removed. If that is the case, could you please consider to reintroduce in Musescore 4, in a update?

I also think that the choir sounds is too quiet for me (even when the sound is at maximum) . But this topic is subjective, so I don't even start a discussion on this topic, although I have to say that when I change the sound of the instrument while the program is playing, instead of the program continues to play the music, it starts from the beggining and I have instruments that is playing in the beginning and anothers playing in the middle of the song and I need to stop every time I change the sound to hear the instruments all lined up at the same time.

Thank you in advance!