For me the PDF scale mode Width or Height is not very helpful. Most PDF files contain white space around the edges, these margins are more important for printing rather than displaying it on a screen. Wondering if a zoom level of a pdf file could be stored with each entry. For example in forScore app this is called Margin adjustment and a simple slider allows to zoom in towards the center of each page, very smart and simple.
No sure if this was already discussed here, but would be a great feature for musician using this app with pdf scores and not just lyrics.