my example was not the best one. if we have an Expression, we would Format the Expression in Chart/table in tab numbers.but there are a lot of fields which we use as dimension.
A better example is a data function. We get data in Format YYYY-MM-DD. Qlikview defines as mixed and Shows exactly that way. We define as date in required Format "DD.MM.YYYY'. I prefer to use the formatting Options of qlikview instead of overwriting in dimension or expressions (num(field1,'#.##0'))
My question is why Qlikview loses the format Settings in document properties.
i got your question earlier, But my intention is different.
Anyhow - Are you applying this for Field and Variable? If you are considering as Variable and Field then it could be the reason some mis understand to troubleshoot. What if, we were re setup the same and using? Does this working, Because it may the cause of Triggers stating in your document as i feel. If not, Wait some time they may offer you as better. I am recommending him to look this thread marcus_sommer
I have also used the the Number tab for changing the format of one of the field but I am not facing such issue.
This line took from Qlik help
Check the Survive Reload option if the formatting is to apply to the document permanently.
my settings are defined, nethertheless I Need to overwrite some field settings
SET MoneyFormat='#.##0,00 €;-#.##0,00 €';
SET TimestampFormat='DD.MM.YYYY hh:mm:ss[.fff]';
AFAIK if a field don't contained only numeric fieldvalues it will be treated as "mixed" format. A single fieldvalue which has a different format respectively not correct interpreted format or maybe is missing or NULL could be enough. But normaly should a defined formating not change whereby I'm not sure what happens if there are scenarios where this field isn't loaded (completely) maybe by some testings or load-errors without canceling or maybe a load without data.
I won't say that I haven't had this case but at moment I don't remember one so that I'm sure it's rather a rarely occurance whereby this isn't very helpful for you.
If you couldn't find a reasonable explanation with the above hint of uncompleted loadings I would try to secure that the field is always filled and numeric maybe with some if-loop or an alt-function like alt(field, 0) as field. Further I could imagine to keep this field always pure numeric without any formatting like 42942 instead of 26.07.2017 and defining all formatting within the document properties.