Is there a way to select multiple folders to move from one account to another (like migrating to a new email host)?
Unfortunately that is not possible. However, if you move a folder, all its sub-folders will move as well.
Another option is to use the export/import option.
If you use Menu > File > Export > Emails, you can select multiple folders and the folder structure will be maintained. Then use Menu > File > Import > Email and select the folder where you exported to previously as the source, and the other account as the destination.