What does a Link Account do?
Link accounts are particularly useful to pull data in from modeled and cube accounts when you want to include dimensionality in your data. For example, let’s say you have your revenue data entered in a cube sheet by a Product dimension. If you pulled this revenue data into a GL account through a regular formula, and then ran a report on the GL account, it would not retain the Product dimension and could not be filtered as such. If you link your GL account to the cube account and run a report on a GL account, you can filter by the Product dimension.
The link account is global and will apply to all versions, although can have Actuals disabled such that you can have hard-coded values or different formulas in just the Actuals version. You can do this by selecting the account on your Manage Accounts screen and under Account Details on the right switching between “Show Actuals if linked accounts has them” and “Enable Actuals for link”.
If you are looking for different versions to hold different formulas/accounts, it would be better to use formulas to pull over the data instead or perhaps set the GL or Custom account as a Data Entry Sheet Type: Cube so that you can add the GL or Custom account directly to a cube for planning and reporting by dimensions.
When an existing account is updated to have the "data entry sheet type" of cube, this will delete data from the account across ALL versions, including locked and hidden.
See Link Account vs. Formula in the Formulas section for additional information that may be relevant.