To account for the LUNA rebrand, you can enter a swap entry in the Trading Tab. On the date of the rebrand, enter a 1:1 swap of LUNA to LUNC. This will move your old LUNA cost basis info to the coin symbol LUNC. Then, you can use the symbol "LUNA" to enter data for any of the new LUNA coin and the symbol "LUNC" for the old LUNA coin.