It sounds as if you have overridden the Text Style Defaults with specific setting for that particular text entity.
Select the text and 'list' it's properties to see if it is as default or has specific values set.
If it has specific values then open 'Properties'.
Delete the specific value(s) and close properties and the text will revert to whatever is set for the Text Style default, and a regen should display it with the defaults for that style.
Alternatively, select a text that is already as the textstyle that you want and copy it's properties to the overriden text:
https://knowledge.autodesk.com/suppo...AD1C2-htm.html
Im intelligent enough to know that I dont know everything; but I'll tell you all about it anyway.