Unfortunately it is currently not possible to choose the label position on a A4 sheet (or any other paper format). Labels will always start top left and then iterate according to the chosen format (e.g. 8xA7).
We are aware that this is not optimal and we are actively working on this feature. A release is currently planned for 2025.
Did you already consider a thermo label printer?
If you plan on sending more than just a few packages/letters per day we recommend using a label printer for efficiency.