Hi @Vanessa Guerrero
In addition to @Lorenzo Kim's suggestion, you can also highlight which columns you want to resize (e.g. use the CTRL key) and drag it wider or smaller. You can also right click onto the column headers and choose Column width.... You'll see all selected columns will resize at the same time.
If you want to adjust columns to the contents, double click onto the lines between the column headers (e.g. A | B) to autofit.
Have fun!
Cheers
Damien
