Add settings to plugins cp section instead of settings page
Solution

In my src/template/index file I added this to make the form work

{% extends "_layouts/cp" %}
{% import "_includes/forms" as forms %}

&lt;form action="" method="post"&gt;
{{ csrfInput() }}

{{ forms.hidden({
    name: 'action',
    value: 'craft-terms-of-service/default/save-tos'
}) }}

{{ forms.hidden({
    name: 'tosCurrentVersion',
    value: now.timestamp
}) }}

{{ forms.lightswitchField({
    label: 'Enable TOS?'|t,
    id: 'tosEnabled',
    name: 'tosEnabled',
    on: craft.craftTermsOfService.get('tosEnabled'),
    first: true
}) }}

{{ forms.textField({
    label: 'Headline'|t('craft-terms-of-service'),
    instructions: 'Enter the headline of your TOS here.'|t('craft-terms-of-service'),
    id: 'tosHeadline',
    name: 'tosHeadline',
    value: craft.craftTermsOfService.get('tosHeadline')
}) }}

{{ craft.craftTermsOfService.redactorField({
    label: 'Terms of Service'|t('craft-terms-of-service'),
    instructions: 'Enter the TOS every user must accept before using the site below.'|t('craft-terms-of-service'),
    name: 'tosBody',
    rows: 4,
    value: craft.craftTermsOfService.get('tosBody')|raw
})|raw }}

&lt;input type="submit" class="submit btn" value="{{ 'Save'|t }}"&gt;




Using the actions/craft-terms-of-service/default/save-tos controller I took the data from the request and updated the data in the plugins table. Also in the form in my index template I used the craft.craftTermsOfService.get variable to fetch the settings from the plugins table and give each form element its appropriate value.

For details, see the controller on github and the variable on github. Note this is the first time I make a plugin, so it's probably a mess, sorry about that.