I cannot seem to be able to enlarge the size of the clone tool or the Dodge & Burn tool.
I have tried keeping my finger on various keys ie. Control/option/shift/Command and then the bracket keys etc and nothing happens it seems the only way to change the size is in the brush size at the top on the toolbar and i am sure it can be changes via one of the keys and then one of the brackets 0 9
Problem resolved.After re-booting the Imac a couple of times and then resetting PS preferences etc everything seems to be working now. Im not sure what happened as i have sat here for ages trying all sorts of things and suddenly all works fine.