I have a text document with columns and cells. I have names in the cells and I want to add a phone # to each name. How do I navigate in the cell to put the phone number below the name?
If your document is really a Writer one (according to the tag), column/row layout is done with a table. In a Writer table, every cell is a sub-document by itself.
Click in a cell and use arrow keys to position the cursor where you want to add text (or click directly on this location). Type text as you would normally do in the main text flow (except for Tab which will send you to the next cell and add a new row when in the last cell).
PS: when asking here, always mention OS name, LO version and save format.
To add a Tab within a cell, press Ctrl+Tab.
To insert a line break in a text document table cell (Writer), press the Enter key.
In calc :
Double-click the cell containing the name
Move the cursor to the end of the name.
Press Ctrl + Enter
Type the phone number below the name.
Press Enter to save the changes.
https://help.libreoffice.org/latest/en-US/text/shared/guide/breaking_lines.html