I recently started using Adobe Acrobat Reader DC free version to annotate the PDF documents I am using for school. I really like a few of the highlighting options but I have found that in order to use them I have to constantly change the opacity. For example, if I want to use yellow then I need to set the opacity at 100% in order to see the highlight well, but if I decide to use the purple in order to see the text the opacity needs to be set at around 30%. The same is true with other colors as well (red is best at around 40%, pink at around 70%, green at around 55%, etc). It gets cumbersome and eats up a lot of time having to constantly change the opacity. It would be great if I could create a set of defaults that works well for me or to be able to set the opacity for each one without constantly having to manually change them. Is there any way to do this or is there another option that would solve my issue?
I've created a (paid-for) tool that adds toolbar icons that allow you to quickly switch between highlight colors. It's also possible to include the opacity level in it, so it will remember a combination of both a color and its opacity level and switch to it when you press one of the buttons. You can find it here: http://try67.blogspot.com/2015/03/acrobatreader-quickly-switch-between.html
If you're interested in that customized version please contact me privately via [try6767 at gmail.com] to discuss it further.