Hey @tombstone_13,
Hope you’re well.
I can’t replicate this problem with the default WordPress themes. So probably your theme using not standard way to generate/render sidebars/widgets. But there is a trick in Custom Sidebars to get this around. At your custom sidebars please click “Edit” first;

Then click the “Advanced – Edit custom wrapper code” checkbox;

Then you will see some extra inputs. You can enter “<h2>” to “Before Title” area, and “</h2>” to “After Title”. Then it should show the title inside h2.
Cheers,
Oguz
@wpmudev-support8 – Thanks a lot.
It’s working….