issue with VoiceOver volume level

iOS and iPadOS

Hello everyone. Hope that everyone is safe and happy. I am having an ishue with voice over. when I use the Alex voice, it can lower down to one percent volium. but when I use other voices such as Samantha, it does not happen. and other text to speech does not increment the voice as good as Alex when I turn the vollium to ten or 20 percent, for example. How can I fix this? thanks.