Decide whether your illustrations are relevant content or decorative elements.
- Relevant content
Anchor your illustrations if they do not have the layout option In line with text. Anchoring has an effect on the logical reading order - the anchored object always follows the paragraph to which it was anchored.
Do not forget to enter the alternative text in the task pane axesWord - Role Mapping.
- Decorative elements
Change the role to Artifact in the context-sensitive task pane axesWord - Role Mapping. An alternative text is then not required.