I usually do not store anything online. I make sure that whatever happens, I would keep them somewhere safe like putting them all on a single txt file and transfer it to a flash drive. As for IMToken, I should write those mnemonic words on a piece of paper, then copy the words in order in the txt file and save it somewhere safe. Don’t ever trust any online service out there, because they have the control to shut down the database and may lose all of your private important information. Just my two satoshis.