Mommies, hello! The baby is still not sitting in the stroller and on t…

Mommies, hello! The baby is still not sitting in the stroller and on the high chair, constantly raising her torso ? She used to sleep in the stroller lying down, but now we go for walks already in the stroller, she raises her torso. What can I do? Change the position of the stroller and the high chair? The stroller is lying down and I don't know how to be ?