There is currently no way to list the spells stored within the Ring of Spell Storing and other similar items. A parameter that creates a form on the character sheet which allows you to select the spells and spell levels (if applicable) stored within (and also display them on the spells section of the character sheet) would be very helpful for tracking this kind of information. Currently, you have to track this on paper or in a different part of the character sheet, which makes it harder than it needs to be to track.

Despite this post almost being a year old, gonna bump it.  Same situation where I cannot find a place to place stored spells on my character sheet.  I have to write in the description and then have other tabs opened up to have the spell descriptions ready.  It would be nice to choose the spells to be stored on the ring somehow.

Click 'Ring of Spell Storing' in the character sheet, click 'Customize' at the top. In the notes section enter the spells you've stored in it.

You could also add them as custom spells with their own attack features and just put "Ring of Spell Storing" in the title.