For more info: https://en.bitcoin.it/wiki/Change
this is stupid i can not see my amount on the https://blockchain.info/address/19ohYAnWK8raeqAdTcbPB6cXYM4LB6JFCH
This means that as soon as the number of receiving addresses plus the number of sent transactions is more than 100, you need to create a new backup. And again for 200, 300, 400, etc... Of course, backing up more frequently than that is perfectly fine too.
ok thx