For your example, 'dynamic' and 'static' work:

Example: Due to its everyday use, the balance of a current account can be quite dynamic, but that of a savings account is more likely to be static.

dynamic adj.
...
2. Characterized by continuous change, activity, or progress ....

[dynamic. (n.d.) American Heritage® Dictionary of the English Language, Fifth Edition. (2011). Retrieved November 17 2015 from http://www.thefreedictionary.com/dynamic]

static adj.
...
3. showing little or no change ....

[static. (n.d.) Random House Kernerman Webster’s College Dictionary. (2010). Retrieved November 17 2015 from http://www.thefreedictionary.com/static]

For your example, 'dynamic' and 'static' work:

Example: Due to its everyday use, the balance of a current account can be quite dynamic, but that of a savings account is more likely to be static.

dynamic adj.
...
3. Characterized by much activity and vigor ....

[dynamic. (n.d.) American Heritage® Dictionary of the English Language, Fifth Edition. (2011). Retrieved November 17 2015 from http://www.thefreedictionary.com/dynamic]

static adj.
...
3. showing little or no change ....

[static. (n.d.) Random House Kernerman Webster’s College Dictionary. (2010). Retrieved November 17 2015 from http://www.thefreedictionary.com/static]