Hi @Jessica LeCoq ,

 go to virtual agent widget and modify this CSS part. Refer attached screenshot

.conversation-button-container {
    position: fixed;
    right: 3rem;
    bottom: 34.5rem; // play around with this to bring top
    z-index: 20;
    /* top: 109px; */
}

Once you find the perfect position copy CSS from inspect element ..>ctrl right click on virtual agen icont--> instance in page editor..> paste it under CSS