Ive started having problems converting PDF files to EPUB/MOBI on Calibre.A way I used was using Mobi Creator to convert the PDF to HTML and then use Calibre to convert that to EPUB.Now in Calibre Ebook viewer the book was perfect and I thought ive finally done it but when I sent it to my ebook its almost unreadable as words just join up together

I cant understand why its fine in Calibre but not on my ebook.
If I dont use Mobi Creator and just convert the PDF to EPUB using Calibre then I get all these weird symbols in the sentences so I dont know what to do to correct this.
Please help