I'm having trouble seeing how that would be happening too if the input is not controlled by a macro or a formula.
I think one thing that I would try is:
Save a copy of the spreadsheet.
Then working in the copy, not the original,
Go to a cell outside the area where data is being entered and displayed.
Type in 6.35
Format the cell so that it displays the way you want it to.
Then copy that to the "bid" cell and see what happens.
If your spreadsheet was working ok and then stopped doing so, my hypothesis would be that somehow in entering data, the correct cell formats got changed. Perhaps this will change it back. If it doesn't work, you still have the original sheet, the way it is now, for more experimenting.
If it was working ok, another thing I would check is to see if there might be an older copy of it somewhere in a backup that could be restored and updated.