For a text file, there are tools that make any changes appear as colored text. These changes are not fully applied until they are "accepted".
In Google Docs, this is called "suggesting mode".
In Microsoft Word, this is called "tracking changes".
If these changes are not accepted, then the edits will not appear in the final version of your file.
For example, in Google Docs if changes aren't accepted, they won't be shown if you download a file or view it with mode set to 'viewing'.
How to turn this tool on/off:
In Google Docs, 3 options:
1. In the upper menu, click "View", go to "Mode", and select one of the 3 modes: Editing, Suggesting, or Viewing. (see screenshot below).
2. Right-click anywhere on the page, and click 'suggest edits' or 'return to editing' (this is shown below the 'comment' option).
3. On the upper toolbar, click the last button on the right side. This drop-down can switch between the 3 modes. (see screenshot below).
Note: when in "Viewing" mode, this button moves to top of page.
In Microsoft Word, 2 options:
1. In the upper menu click on "Review", go to "Tracking" and click on the button for "Track changes"
2. On your keyboard, press "Ctrl + Shift + E"
How to accept changes:
In Google Docs: click on the suggested edit in the right sidebar, and select the check mark button for "Accept suggestion" (see screenshot below).
Or you can first click on the colored text in the file (which will show lines above and below it).
To see all suggested edits in Google Docs, click on "Tools" in the upper menu, and select "Review suggested edits". Then in the window that appears in upper-right, click on arrows for up and down next to "Suggested edits".
In Microsoft Word, 3 options:
1. Right-click on the suggested edit in the text and click accept
2. Click on the suggested edit in the text, and in the upper menu, select "Review" and click "Accept"
3. In the "Revisions" pane, select a change by right-clicking or double-clicking, and select "Accept".
To view the "Revisions" pane, go to "Review" in the upper menu, select "Tracking" and click on "Reviewing pane".
Other info:
Microsoft Word allows you to change how the 'track changes' appear.
Go to "Review" in the upper menu, select "Tracking", and in the lower-right click the arrow for 'change tracking options', and then click on 'advanced options'.