PowerPoint presentations are much smaller when saved to pdf format. Even then it seems they need to be less than 30,000 kb. Consider splitting presentation into parts (Part 1 of 2) and saving the parts to pdf.
To change color on text of a linked item: click on each word individually. To add bold you can highlight entire title and then apply bold.
If you want underline on links just add media to the location. It will put in the title of the link. You can change the text as needed.