Hi there Robyn26,
It's important that your books are organized correctly in order for you to be able to find your transactions easily. QuickBooks Online is a great tool to be able to access your books from anywhere with an internet connection. I can provide some information on migration from QuickBooks Desktop to QuickBooks Online.
When it comes to migrating your data to Quickbooks Online, the chart of accounts created in the import process is based on the chart of accounts in your Desktop system. If you were to want to move money from one account to another, change account types, or edit the account numbers, you would have to do this either in QuickBooks Desktop before migrating your data over, or after the migration is complete within your QuickBooks Online account.
If you have any other questions, feel free to ask them here.