To move Profit and Loss accounts, go to Reports (top bar) > P&L (any P&L Report from the left sidebar)> Edit (top right) > Edit Report > Configure base Profit & Loss (near top middle).

To move Balance Sheet accounts, go to Reports (top bar) > Balance Sheet (any Balance Sheet Report from the left sidebar)> Edit (top right) > Edit Report > Configure base Balance Sheet (near top middle).

Click Expand all to see all accounts in any Financial Category. > Tick the box to the left of the account or accounts you wish to move > Click Move to (top of page)>Select the Financial Category, Group, and Sub Group to which you want to move the account and click on it.

Hint: in a consolidated company, move, group and rename at the consolidated level first, then cascade settings down. See Cascade from parent:  How to move, group and rename financials across entities in a consolidated organisation and transfer settings 

Hint: To quickly find an uploaded account (or set of accounts) by name, use the "Find" command on your computer (Control+F on a PC or Command+F on a Mac). You can then select multiple accounts at a time and move them all at once.