I am transferring a sorcerer character from Roll20 to D&D Beyond and have questions about metamagic use.  How does the character sheet document that I am using metamagic when casting a spell?  For instance, if I use quicken fireball to cast it using my bonus action, then is there anything on the sheet that directs me to choose a viable action, such as casting a cantrip or dodging?  Does the sheet even document sorcery point expenditures, or do I need to track these manually?

There is a counter under the Font of Magic feature under the Features & Traits tab of your sheet. You will have to adjust the counter yourself as it is not automatic.

Thanks!  This helps.  A bit better than Roll20 but still some recordkeeping.