Hi,
Upon checking It's probably not possible to establish a decimal tab in the center column with the ruler in Word for Mac because tabs are a setting for paragraphs. The ruler shows the tab settings for the paragraph you chose when you click on different columns. Each column has its own margin borders.
Here are some more ways to set up decimal tabs in Word for Mac columns. We'll focus on the Tabs dialog box and styles, which give you more control than just using the ruler method and solve the problem of not being able to place tabs in the middle column.
1. How to Use the Tabs Dialog Box to Measure Exactly
This method is quite dependable since you may enter exact measurements and use them on more than one paragraph at a time, making sure that all three columns are the same.
Select all the content that is applicable in all three columns. This makes sure that the tab settings are used in all the paragraphs where you require decimal alignment.
To open the Tabs dialog box,
In the bottom-right corner of the Paragraph group on the Home tab, click the little Paragraph dialog box launcher.
Click the Tabs button at the bottom of the dialog that opens.
Put tabs on each column separately:
In the Tab stop position area, put the measurement for where you want the first column's decimal point to line up (for example, 1.5 inches).
Under Alignment, choose Decimal.
Set it up.
Do this again for the second column (for example, 3.5 inches) and the third column (for example, 5.5 inches), using various places that fit the bounds of each column.
To apply all the tabs, click OK.
2. Using Styles for Paragraphs
If you need to utilize this formatting a lot or in a lot of locations, the best way to keep things consistent and easy to manage is to define a paragraph style.
For an example paragraph, use the Tabs dialog box method above to set up your decimal tabs.
Choose that paragraph, then go to the Home tab and right-click the style you wish to use (or make a new style).
Choose Update [Style Name] to match the selection. Now, any text you format with this style will automatically have the right decimal tab settings for all three columns.
3. Using Tables Instead of Columns
This isn't a straight solution to how to use the columns feature, but if you want to line up data with decimal points, a single-row (or multi-row) table is a better way to do it in Word.
Put in a table with three columns: Click on Table under the Insert tab.
Right-click on any cell and choose Table Properties.
Click the Options button on the Cell tab.
Open the Format > Tabs menu. You can set the decimal tab for the cell or column here.
On a Mac keyboard, press Option + Tab to put the text with the tab alignment into a table cell.
If you want a seamless design, you can hide the table borders later.
Fixing problems with the Ruler
If you have to use the ruler, the problem could be a default tab that is already there or a wrong choice.
Only choose the paragraphs in the second column.
To add a new tab marker to the ruler, double-click on an existing one. This will launch the Tabs dialog box, which lets you control existing tab stops in more detail. You can either clear current tabs or confirm the settings from there.
Before you click in the center column's space, make sure you choose the right Decimal Tab icon (a "T" with a dot) from the tab selection at the far left of the ruler.
Hope that this information helps.
Kind regards,