Decimal separator issue on 4.5.5 self-hosted, white label

I followed the instructions I found here in order to change from 12,345.10 to 12.345,10 by running the query

update countries set decimal_separator = ',', thousand_separator = '.' where id = 840;

I flushed the cache as instructed in the same post, but the decimal separator does not change when issuing a new Invoice or Proforma.

I am using Client country: RomaniaNew, currency: New Romanian Leu, and language: Romanian.

I changed country, currency and language to a few including US and US Dollar, but the issue is still there. Decimal separator does not change with client country and / or currency.

I am doing something wrong, but I cannot figure out what. Any suggestion is highly appreciated!