Modifications:
You can edit a parameter from the Parameters folder in the entities tree.
You can also basify a calculated parameter, i.e. break the associativity of this parameter with its element or calculation. In this case, it will no longer change anymore. For example, a parameter is the length of an edge, if it is basified, it will keep the value of the edge at the moment of the basification and will not no longer change anymore if the edge becomes longer or shorter. Another example: if a parameter is equal to A+B, by basifying it, it will have the A+B value at the basification moment (for example 20mm) and will no longer change.
Basification is an irreversible operation.