Please capitalize where necessary: batavus made an original retro dutch bike with the batavus old dutch bicycle.
A: Batavus made an original retro Dutch bike with the Batavus Old Dutch bicycle.

Please capitalize where necessary: descendants (fig. 3, appears when pressing the "d"-button in the first view)
A: Descendants (fig. 3, appears when pressing the "D"-button in the first view)

Please capitalize where necessary: the columns investigated here are mainly concerned with “cut through” macropores.
A: The columns investigated here are mainly concerned with “cut through” macropores.

Please capitalize where necessary: if your pc opens the dec file, but it's the wrong application, you'll need to change your windows registry file association settings. in other words, windows is associating dec file extensions with the wrong software program.
A:
If your PC opens the DEC file, but it's the wrong application, you'll need to change your Windows registry file association settings. In other words, Windows is associating DEC file extensions with the wrong software program.