I purchased some a samll amount of bitcoin a few years back and stored them on Multibit v. 0.5.15 - recently I've transferred a few with no problems. Earlier this evening I tried to send some to a wallet and the transaction was seen by 1 peer but not confirmed. After reading online it seems that the fee wasn't high enough for it to be picked up by other peers.

Apparently I need to Reset blockchain and transactions to resync my wallet, but I've been advised to upgrade to the latest version of Multibit before doing anything. Does anyone know if it's safe to do this in Multibit HD, or have I got to download the latest version of Multibit Classic? Will I need to extract my keys or can I use the current .wallet file on my mac?

This might be insignificant but I don't want to risk my coins. Any help much appreciated.