I'm looking for a PGN reader and writer for Windows 10. I want to be able to modify and write if I want to enter new lines, all while keeping the format in PGN. I've downloaded ChessX, and it would be perfect except that I can't figure out how to make the board bigger. Alternatively, any other program recommendations would be appreciated.
The board size in ChessX can be easily changed. Close the program windows that you don't need and simply click and drag the borders of the board to increase its size to your liking. The left button of the mouse has to be kept pressed while changing the board size as in most programs. The board can be made almost as large as the size of the monitor. Font size, pieces, etc. can also be easily customized. Newer engines can be added to ChessX.
There are also older versions, e.g., ChessX 1.3.2. This older version is also free and available on the Internet, and I prefer it to newer versions, as it seems to have less clutter in the menus and in terms of windows. Still, you'd probably want to customize the board size, looks and various windows anyway.
Other programs for editing PGNs are less convenient and sometimes even buggy. Even Fritz/ChessBase, in my opinion, is inferior for editing PGN files. Therefore, I advise getting the hang of ChessX for working with PGN files rather than using other chess programs for this purpose. That said, Fritz/ChessBase is a far more advanced program with tons of options and customization and it is irreplaceable in my opinion, especially for pro players. Of course, it also allows editing PGN files but I find it far less convenient than ChessX for that purpose. Please note that Fritz/ChessBase is not free.
To save space, move all the docks to the right.
Then resize the board by grabbing the handle between board and docking widgets and resize the board (see the cursor changing to something like two vertical lines with a two headed arrow). The image below is a sneak preview to ChessX 1.58, but it works the same for all ChessX versions.