Very doable but with a few caveats
Office 2007 added the ribbon bar to the interface, but did not allow you to customize the tabs on the ribbon bar. You could not add, remove, or move buttons on the tabs without using a third-party tool.
Microsoft changed that for Office 2010, 2013 and 2016. Now, you can add commands to the ribbon tabs by adding custom groups to existing tabs and also by adding your own custom tabs with custom groups.
NOTE: You cannot change the default tabs and groups that are built-into Word, or any of the other Office 2010 programs. Commands that you cannot change display grayed out in the list of tabs and groups when customizing the ribbon. Ribbon customization is also specific to the Office program you are working in at the time and does not apply to other Office programs. You must customize the ribbon within each Office program separately.
Customize Office Ribbon
For an example in this post, we will add the Sum button to the Layout tab on Table Tools tab and also to our own custom tab and group.
To add the Sum button the Layout tab on the Table Tools tab, click the File tab.
In the list of options on the left, click Options.
The Word Options dialog box displays. Click the Customize Ribbon option in the list on the left.
Select Commands Not in the Ribbon from the Choose commands from drop-down list.
Scroll down until you find the Sum command and select it.
Select Tool Tabs from the Customize the Ribbon drop-down list. Tool Tabs are tabs that only display when needed. For example, the Table Tools tabs (Design and Layout) display when the cursor is placed in a table.
Scroll down in the list of tabs until you find the Layout tab under Table Tools and select it.
You can only add your own custom buttons to custom groups on tabs. To add a custom group, click New Group.
A New Group (Custom) is added under Layout. Make sure it is selected and then click Rename.
On the Rename dialog box, enter a name for the new group in the Display name edit box. When renaming a custom group, you can also choose an icon to represent that group. To do so, look through the available icons and select one. Click OK.
Make sure Sum is selected in the list on the left, and the newly renamed custom group is selected in the list on the right. Click the Add button to add the Sum command to the new, custom group.
You will see the Sum command listed under the new, custom group on the Layout tab.
Click OK to accept your customizations and close the Word Options dialog box.
In order to access the Layout tab, your cursor must be in a table. Create a small table, if needed, and place the cursor in any cell of the table. Notice the Table Tools tabs that now display. Click the Layout tab.
The Sum button is available in the new custom group you added to the Layout tab.
You can also add buttons to your own custom tab on the ribbon bar. To do this, open the Word Options dialog box as described earlier in this post and select the Customize Ribbon option. Leave Main Tabs selected in the Customize the Ribbon drop-down list. Click the New Tab button.
A New Tab (Custom) is added to the list of tabs, and a new group is automatically added under the new tab. Select the New Tab (Custom) and click Rename.
On the Rename dialog box, enter a name in the Display name edit box and click OK.
To rename the new group created under the new tab, select the New Group (Custom) and click Rename.
On the Rename dialog box, enter a name for the custom group in the Display name edit box. Again, select an icon to represent the group, if desired. Click OK.
Make sure the Sum command is selected in the list on the left and the new, custom group under the new tab is selected in the list on the right. Click Add to add the Sum command to the new group on the new tab.
The Sum command displays under the new group under the new tab.
Before we close the Word Options dialog box and look at our new button on our new tab, let’s export the changes we have made to back them up. Click the Import/Export button at the bottom of the Word Options dialog box. Select Export all customizations from the drop-down menu.
On the File Save dialog box, navigate to the location in which you want to save the Word customizations backup file. Enter a name for the file, keeping the .exportedUI extension. Click Save.
Now, close the Word Options dialog box by clicking OK.
Click on your new tab available on the ribbon bar.
The new custom group displays on the tab containing the Sum button.
If you want to remove your new tab, open the Customize Ribbon screen on the Word Options dialog box as described earlier in this post. Select your new tab from the list on the right and click Remove.
You can also reset the currently selected ribbon tab to its default setup, or reset all your customizations. To do this, click the Reset button and select an option from the drop-down menu.
A confirmation dialog box displays to make sure you want to delete your customizations. Click Yes to continue with the reset action.
If you selected Reset all customizations, all custom ribbon tabs and groups are removed. To restore your custom ribbon tabs and groups, use the Import/Export button on the Customize Ribbon screen on the Word Options dialog box to import the saved .exportedUI file you previously exported.
You can also customize the tabs on the ribbon and the groups on the tabs by changing their order. To do this, open the Customize Ribbon screen on the Word Options dialog box as described earlier in this post. Select a tab you want to move and click the up arrow button or the down arrow button to the right of the list to move the tab.
To move the groups on the tabs, select the group you want to move and click one of the arrow buttons to move it up or down.
As mentioned at the beginning of this post, you cannot remove built-in tabs on the ribbon. However, you can hide tabs if you don’t want them displaying on the ribbon. To hide a tab, select the check box to the left of the tab you want to hide so there is NO check mark in the box. You can always show it again later by selecting the check box so there is a check mark in the box. Enjoy!