I've changed my book manuscript from Word to LibreOffice and the paragraphs all have different indentations

I’ve changed my book manuscript from Word to LibreOffice and the paragraphs all have different indentations so how do I correct it? I’ve followed the instructions in the help section but that hasn’t worked either. I can’t submit a book manuscript like this?

First back up document and work with a copy.

Without having a look at the document as such I would define a paragraph style the way you need it and than reformat all paragraphs. Reformatting can be done by using ctrl+h > options > check paragraph style next select the paragraph style you want to replace and in replace select your new paragraph style.

Depending on how consistent your paragraph style are, it might be necessary to remove direct formatting. ctrl+m or right click > Clear Direct Formatting.