Urgent-My HTML editor never works properly on squeeze page. Erratic, no control,

I have spent months going in circles. Why isn’t what I see what I get. I installed tiny mce and I tried FCKeditor but I didn’t know how to do settings and text was too far down from the top with FCK.

I still have tiny mce. I try using that for font size and the default html editor as well. The page never behaves. Now page is a disaster and I can’t seem to control text.

Now it made other text big, it will have extra spaces between paragraphs, sometimes all text moves center when I want just one line to move center etc. It is not predictable.

Is this wordpress, is this my theme, WHAT IS IT. I have spent months going in circles and I JUST WANT TO MAKE A SQUEEZE PAGE.

CAN ANYONE HELP. Please communicate in easy to understand language for I am not a technical geek.
the theme is flex squeeze. here is the page I am trying to work on now. Text gets big, I can’t get the opening statement bigger, sentences move etc. I have lost my mind. Please help. let me know how I can reach you to do a screen share. thanks.

https://www.yeastfreedietsguide.com/