Why can't I respond "all" to a text sent to a group?

[AC Question]

When someone sends me a text and I am part of a group, when I respond it only goes to the person who sent it, instead of to everyone. Why? and how can I change that?

 

[Ry]

When someone sends me a text and I am part of a group, when I respond it only goes to the person who sent it, instead of to everyone. Why? and how can I change that?

What phone be do you have?

What app are you using for SMS/MMS?