Heading_1 or H1

[Acorn]

Looking at the source code of my website in Google, I note instead of HI, I seem to have Heading_1 instead. As a result my SEO software is telling me I do not have any H1 titles.
Am I missing something here, and how do I change it (if needed of course)
Thanks guys

You might have misread the code: <h1 class="xr_tl Heading_1 xr_s3" style="top: -25.65px;margin:0;">Heading 1</h1>
Heading_1 is a CSS style. h1 is the HTML tag your prose is surrounded by.

Xara codes fails to provide h4 and h5 unfortunately.

Don't change a thing other than ignore SEO.
Can you describe how you looked "at the source code of my website in Google"? I could then check a bit more deeply.

Acorn