hello how can I change the "font size" in all articles? if I try to change in a single article at the time of saving it restores the previous one
thank you

HAllo, you can chane it in customizer -- Advanced - BAse

hello thanks for the answer I changed as attachment but the articles have always remained tahoma and 9px why? I am attaching the result

Just type your text into the editor without formatiing.
If you mark the text then you can format your text. BUt dont do it

Hello sorry but I didn't understand, can you give me an example? thank you

Juat use the editor
youtu.be/QZ_caGrH3k0

hello thanks for the answer, but my question was another, in which class do I find the default: ("tahoma and px 9) because when I insert a new article it puts this data in default and I would like to change it
thank you

Hello,
write your text and the font is based on css and has nothing to do with the shown formation of the editor.
And btw it has nothing to do with the template. Its more like a editor joomla question.