Try this,
Position a drawing object in relation to page, text, or other anchor
You can change this setting for a drawing canvas or a floating object that
is not on a drawing canvas. You cannot change this setting for an inline
object or an object that is on a drawing canvas.
On the Format menu, click the command for the type of object you selected —
for example, AutoShape, Text Box, Picture, or Drawing Canvas — click the
Layout tab, and then click Advanced.
In the Advanced Layout dialog box, click the Picture Position tab, and then
select the options you want for your horizontal and vertical anchors — for
example, margin, page, or paragraph. You can align the object relative to the
anchor, or you can enter a precise numeric position for the object relative
to the anchor.