Strange Behavior In Calc Sheet

Hello,
A certain "Calc" sheet is defined to use certain font and size. In this case its "Tahoma" font, size 12.
However, when I open this sheet and make a new entry, it almost always uses the "Arial" font which is the first in the fonts list , and size 10,
and I have to select the row to correct it.
And another thing, in this "Calc" sheet, two columns are defined as "Currency", and each time I make an entry there I have to click on the currency symbol in the tools bar to enter the currency symbol near the entered number.
What am I doing wrong and how to correct it, it is annoying.
Answers will be appreciated.
Thanks
Motim

Libre office version 6.4.5.2, on windows 10 1903 x64