You don't learn spells from spell scrolls. That is just an indicator of how much lore you need to be able to cast that scroll from a quickslot. (Fighters with no Lore, for example, can't use scrolls at all).
...that number seems to always be red when in your inventory. I'm not sure why. If put in a quickslot of a chr. who has enough Lore, however, they can use it, no worries.
P.S. Wizards can learn spells when you find other Grimores (sp?), and if there are spells in it that the mage doesn't know, you can click a + sign over the spell to learn it. Costs a little copper to do so.
LadyCrimson's post in Wizard Can't learn spells was marked as the answer