Lastmod tags do not get updated

[theoff]

In my website Sitemap [ External links are visible to forum administrators only ],  lastmod tag gets updated only for home page. For the remaining pages lastmod tag shows Feb23. Could you help me in rectifying the sitemap?

[XML-Sitemaps Support]

Hello,

sitemap generator uses "last-modified" http header returned by your server:
https://www.xml-sitemaps.com/http-headers-viewer.html?op=http-headers-viewer&go=1&pageurl=http%3A%2F%2Ftheoff.info%2FTTI.html&se=xmlsitemaps&submit=View